[compiler-rt] [compiler-rt] Remove enable_execute_stack support on arm64 Darwin (PR #158386)

[Saleem Abdulrasool via llvm-commits]

https://github.com/compnerd approved this pull request.

if it was just the page size, that could be adjusted. Android will need 16k pages as well.

https://github.com/llvm/llvm-project/pull/158386