x86-64: Add vector log/logf to libmvec microbenchmark

Add vector log/logf and input files to libmvec microbenchmark.

libmvec-log-inputs:
  70% Normal random distribution
  range: (0.0, DBL_MAX)
  mean: 1.0
  sigma: 50.0
  30% uniform random distribution in range (0.0, DBL_MAX)

libmvec-logf-inputs:
  70% Normal random distribution
  range: (0.0f, FLT_MAX)
  mean: 1.0f
  sigma: 50.0f
  30% uniform random distribution in range (0.0f, FLT_MAX)

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>