[clang] [X86][Driver] Do not add `-evex512` for `-march=native` when the target doesn't support AVX512 (PR #91694)

[Craig Topper via cfe-commits]

topperc wrote:

Could you make getHostCPUFeatures only write the Features["evex512"] entry if Features["avx512f"] is true? Instead of copying Features["avx512f"]?

https://github.com/llvm/llvm-project/pull/91694