cborinternal_p.h: Fix AVX2 build with MSVC

MSVC (and I think ICC too) are lacking the simpler, scalar instructions
to convert from single-precision to half-precision and back. Instead, we
need to use the packed data intrinsics.

Fixes #192.

Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
2 files changed