Clang Assertion `isLValue()' failed in Expr::ClassifyImpl when using imag on a non-complex type in inline asm

### Link for quick verification: https://godbolt.org/z/YdeosbG91
```c
void process_struct() {
float r = 3.14f;
__asm__("" : "=rm"(__imag__ r));
}
```
Go back to `clang 3.6 (assertions)`. Clang trunk and Clang trunk assertion have the different stack dump.
May relate to https://github.com/llvm/llvm-project/issues/62377.

## Stack dump
```console
clang++: /root/llvm-project/llvm/tools/clang/lib/AST/ExprClassification.cpp:57: Cl clang::Expr::ClassifyImpl(clang::ASTContext&, clang::SourceLocation*) const: Assertion `isLValue()' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
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
1. :4:36: current parser token ';'
2. :1:23: parsing function body 'process_struct'
3. :1:23: in compound statement ('{}')
#0 0x00000000042ecab8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42ecab8)
#1 0x00000000042e9ee4 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42e9ee4)
#2 0x000000000422ec88 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#3 0x000073f764e42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x000073f764e969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x000073f764e42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x000073f764e287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x000073f764e2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#8 0x000073f764e39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#9 0x0000000007cd1ed6 clang::Expr::ClassifyImpl(clang::ASTContext&, clang::SourceLocation*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7cd1ed6)
#10 0x0000000007cd20ad clang::Expr::isModifiableLvalue(clang::ASTContext&, clang::SourceLocation*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7cd20ad)
#11 0x0000000007397d68 clang::Sema::ActOnGCCAsmStmt(clang::SourceLocation, bool, bool, unsigned int, unsigned int, clang::IdentifierInfo**, llvm::MutableArrayRef, llvm::MutableArrayRef, clang::Expr*, llvm::MutableArrayRef, unsigned int, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7397d68)
#12 0x0000000006b2e8b7 clang::Parser::ParseAsmStatement(bool&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b2e8b7)
#13 0x0000000006b1b857 clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::LabelDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b1b857)
#14 0x0000000006b1c536 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::LabelDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b1c536)
#15 0x0000000006b24e7e clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b24e7e)
#16 0x0000000006b256ca clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b256ca)
#17 0x0000000006a2b62b clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a2b62b)
#18 0x0000000006a61aed clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a61aed)
#19 0x0000000006a1e78b clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a1e78b)
#20 0x0000000006a1ef7f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a1ef7f)
#21 0x0000000006a26daa clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a26daa)
#22 0x0000000006a27d45 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a27d45)
#23 0x0000000006a281f0 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a281f0)
#24 0x0000000006a08d93 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a08d93)
#25 0x0000000004c4dde8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c4dde8)
#26 0x0000000004f446e5 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f446e5)
#27 0x0000000004ec497e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ec497e)
#28 0x000000000503ea6d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x503ea6d)
#29 0x0000000000de5b4c cc1_main(llvm::ArrayRef, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde5b4c)
#30 0x0000000000ddc59a ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#31 0x0000000000ddc71d int llvm::function_ref&)>::callback_fn&)>(long, llvm::SmallVectorImpl&) driver.cpp:0:0
#32 0x0000000004cc0739 void llvm::function_ref::callback_fn>, std::__cxx11::basic_string, std::allocator>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#33 0x000000000422f124 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x422f124)
#34 0x0000000004cc0d4f clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (.part.0) Job.cpp:0:0
#35 0x0000000004c81832 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c81832)
#36 0x0000000004c827de clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c827de)
#37 0x0000000004c89c35 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c89c35)
#38 0x0000000000de1f41 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde1f41)
#39 0x0000000000c8cf94 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8cf94)
#40 0x000073f764e29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#41 0x000073f764e29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#42 0x0000000000ddc035 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xddc035)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```

Start with the reproducer on Compiler Explorer, then inspect ExprClassification.cpp at the assertion and the Sema::ActOnGCCAsmStmt path shown in the stack dump. Compare behavior for __imag__ on non-complex operands and identify the expected diagnostic or recovery behavior. Done means the reproducer no longer triggers an assertion and regression coverage captures the case.

Written by the indexing model from the issue text.