DetectSimdAndAlignment detects AVX512 on AMD EPYC (znver2)

[kostrzewa]

-- Performing Test _HAVE_AVX512_DOUBLE
-- Performing Test _HAVE_AVX512_DOUBLE - Success
-- SIMD: AVX512 (x86), align=64

[kostrzewa]

Should the autodetection on Grace use a larger alignment? This is what it finds right now:

-- Performing Test _HAVE_SVE
-- Performing Test _HAVE_SVE - Success
-- SIMD: SVE (ARM), align=16

[mtaillefumier]

This issue should be fixed by PR#689. The root cause was that compilation does not imply that a given CPU supports the instructions. To solve the problem, we must compile the test code and run it locally.