InstCombine: add more transforms

C1-X <u C2 -> (X|(C2-1)) == C1
C1-X >u C2 -> (X|C2) == C1
X-C1 <u C2 -> (X & -C2) == C1
X-C1 >u C2 -> (X & ~C2) == C1


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185909 91177308-0d34-0410-b5e6-96231b3b80d8