[AARCH64] Fix HAS_VST1 check if compiled by clang (#49182)
Summary:
Use `UL` suffix supported by all C99 compatible compilers instead of `__AARCH64_UINT64_C`, which is a gcc specific extension
Before the change this check would have failed as follows with a bug-free clang compiler with the following errors:
```
$ clang has_vst1.c
has_vst1.c:5:41: warning: implicit declaration of function '__AARCH64_UINT64_C' is invalid in C99 [-Wimplicit-function-declaration]
v.val[0] = vcombine_f32 (vcreate_f32 (__AARCH64_UINT64_C (0)), vcreate_f32 (__AARCH64_UINT64_C (0)));
^
has_vst1.c:5:79: warning: implicit declaration of function '__AARCH64_UINT64_C' is invalid in C99 [-Wimplicit-function-declaration]
v.val[0] = vcombine_f32 (vcreate_f32 (__AARCH64_UINT64_C (0)), vcreate_f32 (__AARCH64_UINT64_C (0)));
^
has_vst1.c:6:41: warning: implicit declaration of function '__AARCH64_UINT64_C' is invalid in C99 [-Wimplicit-function-declaration]
v.val[1] = vcombine_f32 (vcreate_f32 (__AARCH64_UINT64_C (0)), vcreate_f32 (__AARCH64_UINT64_C (0)));
^
has_vst1.c:6:79: warning: implicit declaration of function '__AARCH64_UINT64_C' is invalid in C99 [-Wimplicit-function-declaration]
v.val[1] = vcombine_f32 (vcreate_f32 (__AARCH64_UINT64_C (0)), vcreate_f32 (__AARCH64_UINT64_C (0)));
^
4 warnings generated.
/tmp/has_vst1-b1e162.o: In function `main':
has_vst1.c:(.text+0x30): undefined reference to `__AARCH64_UINT64_C'
```
Fixes #{issue number}
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49182
Reviewed By: walterddr
Differential Revision: D25471994
Pulled By: malfet
fbshipit-source-id: 0129a6f7aabc46aa117ef719d3a211449cb410f1
