Fix PR3784: If the source of a phi comes from a bb ended with an invoke, make sure...

Fix PR3784: If the source of a phi comes from a bb ended with an invoke, make sure the copy is inserted before the try range (unless it's used as an input to the invoke, then insert it after the last use), not at the end of the bb.

Also re-apply r66140 which was disabled as a workaround.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66976 91177308-0d34-0410-b5e6-96231b3b80d8