[Reland] Improve MKL related logic in FindOpenMP.cmake (#104224)
Reland of PR #94924. The purpose of this PR is to deal with the complicated interactions between MKL and OpenMP.
There are two improvements:
1. It uses a flag to avoid infinite mutual recursion in calling find_package(MKL) and find_package(OpenMP) in some cases.
2. The logic of finding iomp5 is improved and now we can test MKLDNN under ASAN.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104224
Approved by: https://github.com/malfet
