Added declarations for the intrinsics in intrin.h. These are defined in MSVC libs and are needed for
certain spec2000 benchmarks.
In MSVC, these ones seem to be declared in intrin.h, not in the arm64intr.h subheader, so to match closely perhaps we should declare them there as well?
The test, arm64-microsoft-intrinsics.c, doesn't actually include intrin.h nor arm64intr.h, so this test doesn't actually test anything of what this changes (this test would pass just as well before this change). Not sure if a test for this is mandatory or how we handle tests for lib/Headers though.
This just adds declarations. Are these functions provided by some Windows runtime library? Don't you need to implement the intrinsics somewhere in order for the apps that use them to run or link? Ideally, they should be implemented as builtins.