MSVC ARM64 warning on volatile accesses

[ajkhoury]

On the main branch, when building for ARM64 using MSVC, the following warning is emitted:

rpmalloc\rpmalloc.c(277) : warning C4746: volatile access of '' is subject to /volatile:<iso|ms> setting; consider using __iso_volatile_load/store intrinsic functions

Could you use the __iso_volatile_load/store intrinsic functions for the atomic_load32, atomic_store32, atomic_load64, atomic_store32_release, atomic_store_ptr, and atomic_store_ptr_release functions?

[mjansson]

Could you provide a PR with the modifications please - and if possible, if you have access to a Windows ARM64 machine, run the tests?

[mjansson]

Windows ARM64 support should now be complete on the develop branch