ART: Improve fused compare long branch

The code generated by a fused compare long with an immediate value is
much longer than comparing to a runtime value. Rewrite the code to
improve it.

The special cases are == or != to 0, and whether the source is a
temporary value or not.  Try to handle all of these well.  For all
except == and !=, we can use a 'cmp' instruction for the upper word, in
order to set the carry flag properly, rather than a 'sub' into a temp.

Also, we have to handle the <= and > cases properly, in order to get the
correct code generated, in the same manner as
X86Mir2Lir::GenFusedLongCmpBranch().

Change-Id: Ic29bf89ff2c06916d7fc996926997888ea013ba7
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>