x86: further refine SSE check (SSE4a, SHA, GFNI)

x86: further refine SSE check (SSE4a, SHA, GFNI)

In  ("x86: extend SSE check to PCLMULQDQ, AES, and GFNI insns") I went
both a little too far and not quite far enough:
- GFNI insns also have AVX512 variants, which also shouldn't get
  diagnosed,
- SSE4a insns should get diagnosed just like SSE4.x ones,
- SHA insns should get diagnosed just like PCLMULQDQ or AES ones.