Older gcc support

[Nor7th]

https://github.com/intel/xFasterTransformer/blob/master/CMakeLists.txt#L46-L70 This bf16 check only works for gcc whose version >= 10.1.

What about older gcc versions which even don't support avx512? Can they compile and work normally? If not supported, is it until runtime that error message can be found?

Your Q&A mentions this should run on AVX512/AMX, but seems the CMakeLists.txt do not have specific logic/hints to guarantee this?