Simplify more cases of logical ops of masked icmps.

Summary:
For example,

((X & 255) != 0) && ((X & 15) == 8) -> ((X & 15) == 8).
((X & 7) != 0) && ((X & 15) == 8) -> false.

Reviewers: davidxl

Reviewed By: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43835

llvm-svn: 327450