[PowerPC] Optimize compares fed by ANDISo

Both ANDIo and ANDISo (and the 64-bit versions) are record-form instructions.
When optimizing compares, we handle the former in order to eliminate the compare
instruction but not the latter. This patch just adds the latter to the set of
instructions we optimize.
The reason these instructions need to be handled separately is that they are not
part of the RecFormRel map (since they don't have a non-record-form). The
missing "and-immediate-shifted" is just an oversight in the initial
implementation.

Differential revision: https://reviews.llvm.org/D51353

llvm-svn: 342472