Add some tests for SimplifyCFG's ConstantFoldTerminator(). NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223395 91177308-0d34-0410-b5e6-96231b3b80d8
Add some tests for SimplifyCFG's TurnSwitchRangeIntoICmp(). NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223396 91177308-0d34-0410-b5e6-96231b3b80d8