[LVI] Teach LVI to reason about ORs of icmps similar to how it reasons about ANDs of icmps

Summary: LVI can reason about an AND of icmps on the true dest of a branch. I believe we can do similar for the false dest of ORs. This allows us to get the same answer for the demorganed versions of some of the AND test cases as you can see.

Reviewers: anna, reames

Reviewed By: reames

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D34431

llvm-svn: 306076