LVI: Recognize the form instcombine canonicalizes range checks into when forming constant ranges.

This could probably be made a lot smarter, but this is a common case and doesn't require LVI to scan a lot
of code. With this change CVP can optimize away the "shift == 0" case in Hashing.h that only gets hit when
"shift" is in a range not containing 0.

llvm-svn: 151919