[clang] [clang] [ARM] Explicitly enable NEON for Windows/Darwin targets (PR #122095)

[Dan Albert via cfe-commits]

DanAlbert wrote:

It's over 4 years old so unfortunately I'm probably not much help beyond what's already written on the old review/commit. At the time we were still using GAS though, so perhaps that made it more meaningful? If vfpv3 was already the default FPU for armv7 at the time then it's probable that I just misunderstood.

https://github.com/llvm/llvm-project/pull/122095