When extracting a basic block that ends in an 'invoke' instruction, we need to

When extracting a basic block that ends in an 'invoke' instruction, we need to
extract its associated landing pad block as well. However, that landing pad
block may have more than one predecessor. So split the landing pad block so that
individual landing pads have only one predecessor.

This type of transformation may produce a false positive with bugpoint.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140173 91177308-0d34-0410-b5e6-96231b3b80d8