[InstCombine] Improve the expansion in SimplifyUsingDistributiveLaws to handle cases...

[InstCombine] Improve the expansion in SimplifyUsingDistributiveLaws to handle cases where one side doesn't simplify, but the other side resolves to an identity value

Summary:
If one side simplifies to the identity value for inner opcode, we can replace the value with just the operation that can't be simplified.

I've removed a couple now unneeded special cases in visitAnd and visitOr. There are probably other cases I missed.

Reviewers: spatel, majnemer, hfinkel, dberlin

Reviewed By: spatel

Subscribers: grandinj, llvm-commits, spatel

Differential Revision: https://reviews.llvm.org/D35451

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308111 91177308-0d34-0410-b5e6-96231b3b80d8