[gentoo-dev] Augmenting the CPU_FLAGS_X86 list and creating CPU_FLAGS_PPC + CPU_FLAGS_ARM

[David Seifert]

Dear friends,
while version bumping sci-libs/fftw, I've noticed our CPU_FLAGS_X86
list could be expanded a bit:

avx512 - introduced with Skylake and Knights Landing

I also propose creating a CPU_FLAGS_PPC variable containing (at least):

altivec - PowerPC's SSE
vsx - PowerPC's AVX

Finally, I also propose creating CPU_FLAGS_ARM variable containing:

neon

Any ideas? Currently cpu-feature flags for non-x86 are package local,
whereas making them globally available makes masking easier for non-
applicable archs etc. and makes enabling them easier for users.

David