Merging r168711: into the 3.2 release branch.

SCEV: Even if the latch terminator is foldable we can't deduce the result of an unrelated condition with it.

Fixes PR14432.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_32@168973 91177308-0d34-0410-b5e6-96231b3b80d8