[Clang] On GCC, C23 `typeof` strips `noreturn` attribute on function pointers

https://godbolt.org/z/e8M18778s
```C
[[gnu::noreturn]]
extern void(*fptr)(void);

int typeof_ext(int i, __typeof(fptr) p) {
p();
return i; // not emitted because p is noreturn
}

int typeof_std(int i, typeof(fptr) p) {
p();
return i; // emitted on GCC C23
}
```

When under C23 and using the standard (not underscored) spelling of `typeof`, GCC would remove the `noreturn` attribute from the function pointer type.
From GCC's commit message (https://github.com/gcc-mirror/gcc/commit/fa258f6894801aef6785f0327594dc803da63fbd) this seems to be intentional.
Could be dangerous if someone rely on this behavior and only test with GCC.

Start with the Compiler Explorer reproduction at https://godbolt.org/z/e8M18778s and compare the standard and underscored typeof spellings under C23. Trace Clang's C23 typeof handling and add a regression test covering preservation of the noreturn attribute on function-pointer types; done means the two spellings have the intended, consistent behavior.

Written by the indexing model from the issue text.