[LoopStrengthReduce] Don't rewrite PHIs with incoming values from CatchSwitches

Bail out if we have a PHI on an EHPad that gets a value from a
CatchSwitchInst.  Because the CatchSwitchInst cannot be split, there is
no good place to stick any instructions.

This fixes PR26373.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259702 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed