Support CMOV for x86_64 Select

If possible, generate CMOV to implement HSelect.  Tricky cases are
an FP condition (no single CC generated), FP inputs (no FP CMOV)
and when the condition is a boolean or not emitted at the use site.
In these cases, keep using the existing HSelect code.

Added Load32BitValue for int and FP and used that to remove code
duplication. Added minimal checker test for int/long CMOV generation.

Change-Id: Id71e515f0afa5a30f53c5de3a5244de1ea429aae
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>