[Clang][PowerPC] PPC min/max builtins with fewer than 4 arguments trigger Assertion `Arg < getNumArgs() && "Arg access out of range!"' failed.

Reproducer：
A fuzzing tool generated the following test case:
https://godbolt.org/z/b4ajqabx4

```c++
void test_builtin_ppc_maxminfe(long double a, long double b, long double c, long double d) {

long double res;
res = __builtin_ppc_maxfe(a, b, c);

}
```
With Clang trunk and:

```
--target=powerpc64le-linux-gnu
```

Clang triggers:

```
clang++: /root/llvm-project/llvm/tools/clang/include/clang/AST/Expr.h:3163: const clang::Expr* clang::CallExpr::getArg(unsigned int) const: Assertion `Arg < getNumArgs() && "Arg access out of range!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
Stack dump:
0. Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics --target=powerpc64le-linux-gnu
1. parser at end of file
2. :2:6: LLVM IR generation of declaration 'test_builtin_ppc_maxminfe'
3. :2:6: Generating code for declaration 'test_builtin_ppc_maxminfe'
#0 0x000000000448ebf8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x448ebf8)
#1 0x000000000448baa4 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x448baa4)
#2 0x000000000448c0dc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x448c0dc)
#3 0x00000000043ca9d8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#4 0x00007079df845330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
#5 0x00007079df89ec0c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9ec0c)
#6 0x00007079df84527e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
#7 0x00007079df8288ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
#8 0x00007079df82881b (/lib/x86_64-linux-gnu/libc.so.6+0x2881b)
#9 0x00007079df83b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#10 0x0000000004cc284a (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4cc284a)
#11 0x0000000004d39a6d clang::CodeGen::CodeGenFunction::EmitPPCBuiltinExpr(unsigned int, clang::CallExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4d39a6d)
#12 0x0000000004e56ca5 clang::CodeGen::CodeGenFunction::EmitBuiltinExpr(clang::GlobalDecl, unsigned int, clang::CallExpr const*, clang::CodeGen::ReturnValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4e56ca5)
#13 0x0000000004981f5e clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4981f5e)
#14 0x00000000049f134c (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprScalar.cpp:0:0
#15 0x00000000049e68a0 clang::StmtVisitorBase::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#16 0x00000000049ec34c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x49ec34c)
#17 0x000000000495528e clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x495528e)
#18 0x000000000497df21 clang::CodeGen::CodeGenFunction::EmitBinaryOperatorLValue(clang::BinaryOperator const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x497df21)
#19 0x0000000004983597 clang::CodeGen::CodeGenFunction::EmitLValueHelper(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4983597)
#20 0x0000000004983f07 void llvm::function_ref::callback_fn(long) CGExpr.cpp:0:0
#21 0x00000000088e0f41 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x88e0f41)
#22 0x000000000494804c clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x494804c)
#23 0x000000000497cd7e clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x497cd7e)
#24 0x0000000004b18a7b clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b18a7b)
#25 0x0000000004b20d4b clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b20d4b)
#26 0x0000000004b89846 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b89846)
#27 0x0000000004b9f264 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b9f264)
#28 0x0000000004c0fada clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c0fada)
#29 0x0000000004c08ec4 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c08ec4)
#30 0x0000000004c09c10 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c09c10)
#31 0x0000000004c16d21 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#32 0x0000000004f95069 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#33 0x0000000004f86114 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f86114)
#34 0x0000000006dac204 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6dac204)
#35 0x0000000004f92ef8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f92ef8)
#36 0x00000000052bd7b8 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x52bd7b8)
#37 0x000000000524baed clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x524baed)
#38 0x00000000053927ed clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x53927ed)
#39 0x0000000000dae91c cc1_main(llvm::ArrayRef, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdae91c)
#40 0x0000000000da553a ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#41 0x0000000000da56bd int llvm::function_ref&)>::callback_fn&)>(long, llvm::SmallVectorImpl&) driver.cpp:0:0
#42 0x000000000500bbc9 void llvm::function_ref::callback_fn>, std::__cxx11::basic_string, std::allocator>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#43 0x00000000043cae14 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43cae14)
#44 0x000000000500c735 clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (.part.0) Job.cpp:0:0
#45 0x0000000004fc43e2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fc43e2)
#46 0x0000000004fc8d47 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fc8d47)
#47 0x0000000004fd3415 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fd3415)
#48 0x0000000000daae1a clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdaae1a)
#49 0x0000000000cc6b4a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xcc6b4a)
#50 0x00007079df82a1ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#51 0x00007079df82a28b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#52 0x0000000000da4ee5 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda4ee5)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Compiler returned: 134
```

I traced this issue back to Clang 15.

After further investigation, I found that the following PPC builtins also trigger the same assertion when called with fewer than 4 arguments:
https://godbolt.org/z/6TvnePara

```c++
void test_maxfl(double a, double b, double c) {
__builtin_ppc_maxfl(a, b, c);
}

void test_maxfs(float a, float b, float c) {
__builtin_ppc_maxfs(a, b, c);
}

void test_minfe(long double a, long double b, long double c) {
__builtin_ppc_minfe(a, b, c);
}

void test_minfl(double a, double b, double c) {
__builtin_ppc_minfl(a, b, c);
}

void test_minfs(float a, float b, float c) {
__builtin_ppc_minfs(a, b, c);
}
```

Start with the reproducer on Compiler Explorer using Clang trunk and --target=powerpc64le-linux-gnu, then inspect clang::CodeGen::CodeGenFunction::EmitPPCBuiltinExpr from the stack trace. Exercise the listed PPC max/min builtins with fewer than four arguments and verify compilation no longer triggers the Arg access out of range assertion.

Written by the indexing model from the issue text.