NT2 format: Only use OMP+SSE2 for AVX or XOP. Older CPUs won't do well.
Dynamic OMP bugfix.
Merge branch 'bleeding-jumbo' into memdbg

* bleeding-jumbo:
  Dynamic OMP bugfix.
  NT2 format: Only use OMP+SSE2 for AVX or XOP. Older CPUs won't do well.