error: 'mi_posix_memalign' is missing exception specification 'noexcept'

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### Environment

macOS 10.13, Xcode AppleClang 10.0.0, -std=c++17 -fno-exceptions -stdlib=libc++
macOS 12, Xcode AppleClang 13.1.6, -std=c++17 -fno-exceptions -stdlib=libc++
mimalloc v2.1.2

### Details

After all macro expansions, `mi_posix_memalign` is declared like
```
int mi_posix_memalign(void** p, size_t alignment, size_t size) noexcept;
```
and this substitutes clang `posix_memalign` and conflicts with it, that seems to be declared without `noexcept`:
```
extern "C" int posix_memalign(void **__memptr, size_t __alignment, size_t __size);
```
The whole error message:
```
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/13.1.6/include/mm_malloc.h:25:16: error: 'mi_posix_memalign' is missing exception specification 'noexcept'
extern "C" int posix_memalign(void **__memptr, size_t __alignment, size_t __size);
^
/Users/buildbox/Source/actions-runner/_work/client/client/core/../third_party/mimalloc/include/mimalloc-override.h:54:33: note: expanded from macro 'posix_memalign'
#define posix_memalign(p,a,n) mi_posix_memalign(p,a,n)
^
/Users/buildbox/Source/actions-runner/_work/client/client/core/../third_party/mimalloc/include/mimalloc.h:383:20: note: previous declaration is here
mi_decl_export int mi_posix_memalign(void** p, size_t alignment, size_t size) mi_attr_noexcept;
^
```

Inspect the macro and declaration in include/mimalloc-override.h and include/mimalloc.h, then compare them with Clang's mm_malloc.h declaration under the reported macOS and C++17 flags. Reproduce the compile error with -fno-exceptions; done means the declarations no longer conflict and the affected configurations compile successfully.

Written by the indexing model from the issue text.