x86-64: Add vector log1p/log1pf to libmvec microbenchmark

x86-64: Add vector log1p/log1pf to libmvec microbenchmark

Add vector log1p/log1pf and input files to libmvec microbenchmark.

libmvec-log1p-inputs:
  70% Normal random distribution
  range: (-1.0, DBL_MAX)
  mean: 0.0
  sigma: 50.0
  30% uniform random distribution in range (-1.0, 1.0e6)

libmvec-log1pf-inputs:
  70% Normal random distribution
  range: (-1.0f, FLT_MAX)
  mean: 0.0f
  sigma: 50.0f
  30% uniform random distribution in range (-1.0f, 1.0e6f)

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