This is an alternative of D157485 and a pre-feature to support AVX10.
AVX10 Architecture Specification: https://cdrdv2.intel.com/v1/dl/getContent/784267
AVX10 Technical Paper: https://cdrdv2.intel.com/v1/dl/getContent/784343
RFC: https://discourse.llvm.org/t/rfc-design-for-avx10-feature-support/72661
Based on the feedbacks from LLVM and GCC community, we have agreed to
start from supporting -m[no-]evex512 on existing AVX512 features.
The option -mno-evex512 can be used with -mavx512xxx to build
binaries that can run on both legacy AVX512 targets and AVX10-256.
There're still arguments about what's the expected behavior when this
option as well as -mavx512xxx used together with -mavx10.1-256. We
decided to defer the support of -mavx10.1 after we made consensus.
Or furthermore, we start from supporting AVX10.2 and not providing any
AVX10.1 options.
Remove Feature argument and hardcode to "avx" now that it only has 1 (avx) caller?