Fuse long and FP compare & condition on x86/x86-64 in Optimizing.

This is a preliminary implementation of fusing long/float/double
compares with conditions to avoid materializing the result from the
compare and condition.

The information from a HCompare is transferred to the HCondition if it
is legal.  There must be only a single use of the HCompare, the HCompare
and HCondition must be in the same block, the HCondition must not need
materialization.

Added GetOppositeCondition() to HCondition to return the flipped
condition.

Bug: 21120453
Change-Id: I1f1db206e6dc336270cd71070ed3232dedc754d6
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>