[X86] Enable the add with 128 -> sub with -128 encoding trick with X86ISD::ADD...

[X86] Enable the add with 128 -> sub with -128 encoding trick with X86ISD::ADD when the carry flag isn't used.

This allows us to use an 8-bit sign extended immediate instead of a 16 or 32 bit immediate.

Also do similar for 0x80000000 with 64-bit adds to avoid having to use a movabsq.

llvm-svn: 355485