[MacOS] Cross compile stub when building for M1 on x86 (#54046)
Summary:
Also rename `CROSS_COMPILE_ARM` to `CROSS_COMPILE_ARM64`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54046
Reviewed By: walterddr
Differential Revision: D27071928
Pulled By: malfet
fbshipit-source-id: 9143cd5d110ed67f0609f0a4bbb20922012ee665
