[clang] Assertion `PreferredAlign == CharUnits::fromQuantity(4) && "No need to upgrade the alignment value."` failed

The following code:

```cpp
#define ATTR __attribute__((__ms_struct__))
struct _struct_9
{
double member_3;
}
ATTR;
typedef struct _struct_9 struct_9;
struct_0 test_struct_0 = { 123 }
```

Resulted in this output:
```
/tmp/test.cpp:8:1: error: unknown type name 'struct_0'; did you mean 'struct_9'?
8 | struct_0 test_struct_0 = { 123 }
| ^~~~~~~~
| struct_9
/tmp/test.cpp:7:26: note: 'struct_9' declared here
7 | typedef struct _struct_9 struct_9;
| ^
clang-24: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-project/clang/lib/AST/RecordLayoutBuilder.cpp:1999: {anonymous}::ItaniumRecordLayoutBuilder::LayoutField(const clang::FieldDecl*, bool)::: Assertion `PreferredAlign == CharUnits::fromQuantity(4) && "No need to upgrade the alignment value."' 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: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin/clang-24 -cc1 -triple powerpc64-ibm-aix -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name test.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -fxl-pragma-pack -fno-sized-deallocation -target-cpu pwr7 -target-feature +modern-aix-as -mfloat-abi hard -gstrict-dwarf -gno-column-info -fdebug-compilation-dir=/home/fuzz/WorkSpace/fusion-fuzz/projects/clang -fdata-sections -fcoverage-compilation-dir=/home/fuzz/WorkSpace/fusion-fuzz/projects/clang -resource-dir /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/lib/clang/24 -internal-isystem /opt/IBM/openxlCSDK/include/c++/v1 -D__LIBC_NO_CPP_MATH_OVERLOADS__ -internal-isystem /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/lib/clang/24/include/ppc_wrappers -internal-isystem /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/lib/clang/24/include -internal-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fno-signed-char -fno-use-cxa-atexit -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -o /tmp/test-6d4352.o -x c++ /tmp/test.cpp
1. parser at end of file
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0 clang-24 0x00005ce11ad8d329 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 121
1 clang-24 0x00005ce11ad89fec llvm::sys::RunSignalHandlers() + 76
2 clang-24 0x00005ce11ad8a156
3 clang-24 0x00005ce11ad8a21c
4 libc.so.6 0x00007c6a914d3520
5 libc.so.6 0x00007c6a915279bc pthread_kill + 300
6 libc.so.6 0x00007c6a914d3476 raise + 22
7 libc.so.6 0x00007c6a914b97f3 abort + 211
8 libc.so.6 0x00007c6a914b971b
9 libc.so.6 0x00007c6a914cae96
10 clang-24 0x00005ce11edebfa5
11 clang-24 0x00005ce11edfaf88
12 clang-24 0x00005ce11edfb02a
13 clang-24 0x00005ce11edf4ce8 clang::ASTContext::getASTRecordLayout(clang::RecordDecl const*) const + 1528
14 clang-24 0x00005ce11ea12da5
15 clang-24 0x00005ce11ea0a0ae
16 clang-24 0x00005ce11ea0e288
17 clang-24 0x00005ce11ea7059a clang::Expr::EvaluateAsInitializer(clang::ASTContext const&, clang::VarDecl const*, clang::Expr::EvalResult&, bool) const + 570
18 clang-24 0x00005ce11e836522 clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl>*, bool) const + 306
19 clang-24 0x00005ce11e836ab6 clang::VarDecl::checkForConstantInitialization(llvm::SmallVectorImpl>&) const + 118
20 clang-24 0x00005ce11d993739 clang::Sema::CheckCompleteVariableDeclaration(clang::VarDecl*) + 2841
21 clang-24 0x00005ce11d9c6e91 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) + 1105
22 clang-24 0x00005ce11d5cf7d1 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) + 3313
23 clang-24 0x00005ce11d5e936c clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 2844
24 clang-24 0x00005ce11d598fac clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) + 924
25 clang-24 0x00005ce11d59978f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) + 975
26 clang-24 0x00005ce11d5a5646 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 598
27 clang-24 0x00005ce11d5a66ff clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) + 575
28 clang-24 0x00005ce11d583632 clang::ParseAST(clang::Sema&, bool, bool) + 530
29 clang-24 0x00005ce11bc24061 clang::FrontendAction::Execute() + 65
30 clang-24 0x00005ce11bbade65 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1589
31 clang-24 0x00005ce11bcfbde3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 467
32 clang-24 0x00005ce118b5733e cc1_main(llvm::ArrayRef, char const*, void*) + 7166
33 clang-24 0x00005ce118b4d13a
34 clang-24 0x00005ce118b51425 clang_main(int, char**, llvm::ToolContext const&) + 1941
35 clang-24 0x00005ce118a8e7f1 main + 113
36 libc.so.6 0x00007c6a914bad90
37 libc.so.6 0x00007c6a914bae40 __libc_start_main + 128
38 clang-24 0x00005ce118b4c765 _start + 37
clang++: error: unable to execute command: Aborted (core dumped)
clang++: error: clang frontend command failed with exit code -2 (use -v to see invocation)
clang version 24.0.0git (https://github.com/llvm/llvm-project.git 0976d75180f482c1175ea1f204f9bfd56dd163b1)
Target: powerpc64-ibm-aix
Thread model: posix
InstalledDir: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin
Build config: +assertions
clang++: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING CRASH REPRODUCER FILES TO THE BUG REPORT:
clang++: note: diagnostic msg: /tmp/test-332676.cpp
clang++: note: diagnostic msg: /tmp/test-332676.sh
clang++: note: diagnostic msg:

********************
Aborted (core dumped)
```

To reproduce:
```
/home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin/clang++ -target powerpc64-ibm-aix ./test.cpp
```

Trunk: https://godbolt.org/z/YoWcP6zs1

Goes back to clang-12: https://godbolt.org/z/3nnrT8Gzx

Compiler version:
```
clang version 24.0.0git (https://github.com/llvm/llvm-project.git 0976d75180f482c1175ea1f204f9bfd56dd163b1)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin
Build config: +assertions
```

*This bug was found by [fusion-fuzz](https://github.com/fusion-fuzz/fusion-fuzz)*

The assertion is in clang/lib/AST/RecordLayoutBuilder.cpp:1999. Start by reproducing the crash with test.cpp and the provided powerpc64-ibm-aix clang++ command, then inspect the record-layout path reached from the stack trace. Done means the input no longer aborts clang while preserving the reported diagnostic behavior.

Written by the indexing model from the issue text.