[InstCombine] Add test cases for known bits simplifications for comparisons that don't depend on constant RHS. NFC

This shows some missing simplifications for sge/sle/uge/ule relative to their non-equality counterparts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314031 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed