[clang] assertion `LateParsedObjCMethods.empty()` failed.

The following code:

```objective-c++
@implementation NSArray
@interface NSIndexSet
#include
vint16mf2_t test_vwmaccsu_vx_i16mf2(vint16mf2_t vd, int8_t rs1, vuint8mf4_t vs2, size_t vl) {}
```

Resulted in this output:
```
/tmp/test.mm:1:17: warning: cannot find interface declaration for 'NSArray'
1 | @implementation NSArray
| ^
/tmp/test.mm:1:17: warning: class 'NSArray' defined without specifying a base class [-Wobjc-root-class]
/tmp/test.mm:1:24: note: add a super class to fix this problem
1 | @implementation NSArray
| ^
/tmp/test.mm:2:1: error: missing '@end'
2 | @interface NSIndexSet
| ^
/tmp/test.mm:1:1: note: implementation started here
1 | @implementation NSArray
| ^
/tmp/test.mm:3:10: fatal error: 'riscv_vector.h' file not found
3 | #include
| ^~~~~~~~~~~~~~~~
clang-24: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-project/clang/lib/Parse/ParseObjc.cpp:2039: clang::Parser::ObjCImplParsingDataRAII::~ObjCImplParsingDataRAII(): Assertion `LateParsedObjCMethods.empty()' 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 x86_64-unknown-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name test.mm -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/home/fuzz/WorkSpace/fusion-fuzz/projects/clang -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 /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/x86_64-linux-gnu/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/backward -internal-isystem /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/lib/clang/24/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fobjc-runtime=gcc -fobjc-encode-cxx-class-template-spec -fobjc-exceptions -fcxx-exceptions -fexceptions -faddrsig -fdwarf2-cfi-asm -o /tmp/test-30edf5.o -x objective-c++ /tmp/test.mm
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 0x0000560b47e660f9 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 121
1 clang-24 0x0000560b47e62dcc llvm::sys::RunSignalHandlers() + 76
2 clang-24 0x0000560b47e62f32
3 clang-24 0x0000560b47e62fec
4 libc.so.6 0x00007f1c7c880520
5 libc.so.6 0x00007f1c7c8d49fc pthread_kill + 300
6 libc.so.6 0x00007f1c7c880476 raise + 22
7 libc.so.6 0x00007f1c7c8667f3 abort + 211
8 libc.so.6 0x00007f1c7c86671b
9 libc.so.6 0x00007f1c7c877e96
10 clang-24 0x0000560b4a6ad2ce clang::Parser::ObjCImplParsingDataRAII::~ObjCImplParsingDataRAII() + 1566
11 clang-24 0x0000560b4a6b11a8 clang::Parser::ParseObjCAtImplementationDeclaration(clang::SourceLocation, clang::ParsedAttributes&) + 1064
12 clang-24 0x0000560b4a605e70 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 2720
13 clang-24 0x0000560b4a6067df clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) + 575
14 clang-24 0x0000560b4a606bf4 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) + 68
15 clang-24 0x0000560b4a5e36db clang::ParseAST(clang::Sema&, bool, bool) + 539
16 clang-24 0x0000560b48b5c071 clang::FrontendAction::Execute() + 65
17 clang-24 0x0000560b48ae5c65 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1589
18 clang-24 0x0000560b48c37ea3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 467
19 clang-24 0x0000560b4683ac96 cc1_main(llvm::ArrayRef, char const*, void*) + 7046
20 clang-24 0x0000560b46830a2a
21 clang-24 0x0000560b46834dd5 clang_main(int, char**, llvm::ToolContext const&) + 1893
22 clang-24 0x0000560b467887a1 main + 113
23 libc.so.6 0x00007f1c7c867d90
24 libc.so.6 0x00007f1c7c867e40 __libc_start_main + 128
25 clang-24 0x0000560b46830055 _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 aefba88f46a6e55645c848f58f6ba56944d5ae62)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin
Build config: +assertions
clang++: note: diagnostic msg: Error generating preprocessed source(s).
Aborted (core dumped)
```

To reproduce:
```
/home/fuzz/WorkSpace/fusion-fuzz/projects/clang/llvm-clang-install/bin/clang++ ./test.mm
```

Compiler version:
```
clang version 24.0.0git (https://github.com/llvm/llvm-project.git aefba88f46a6e55645c848f58f6ba56944d5ae62)
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)*

Start with the test.mm reproducer and run the clang++ command shown in the issue. Read clang/lib/Parse/ParseObjc.cpp around the ObjCImplParsingDataRAII destructor and the ParseObjCAtImplementationDeclaration entry point. Done means this input produces diagnostics without triggering the LateParsedObjCMethods assertion.

Written by the indexing model from the issue text.