cpuinfo: Added SDL_HasAVX512F().

This checks for the "foundation" AVX-512 instructions (that all AVX-512
compatible CPUs support).

--HG--
extra : rebase_source : 2857dd04072e2f897e18665d0a4fe2837c06ed9b
extra : histedit_source : 67d0b925bceb2ed2a8f37b5783f2b755e796031f
5 files changed