[InstCombine] add/move tests for or-of-icmps; NFC

If we had these tests, the bug caused by https://reviews.llvm.org/rL299851 would have been caught sooner.
There's also an assert in the code that should have caught that bug, but the assert line itself has a bug.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300201 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed