fixes for AVX detection (#17915)

fixes for AVX detection (#17915)

Summary:
Our AVX2 routines use functions such as _mm256_extract_epi64
that do not exist on 32 bit systems even when they have AVX2.
This disables AVX2 when _mm256_extract_epi64 does not exist.

This fixes the "local" part of #17901 (except disabling FBGEMM),
but there also is sleef to be updated and NNPACK to be fixed,
see the bug report for further discussion.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17915

Differential Revision: D14437338

Pulled By: soumith

fbshipit-source-id: d4ef7e0801b5d1222a855a38ec207dd88b4680da