Partial revert of 132882.

Dan noted that this would work on the case shown on the commit message. I think
the case that was failing was a bb ending with a redundant conditional jump:

...
jne foo

foo:
...

I was unable to find any such case in the tests or in a debug build of clang,
so I will revert this part of the patch and watch the bots.

llvm-svn: 133004