Fix two pretty serious bugs:

  1. Each time the loop extractor extracted a loop, we would leak a module.
  2. When we extracted a loop, we didn't add the new function to the list of
     miscompiled functions.  Thus if the bug was in a loop nest and we
     extracted it, we could actually *LOSE THE BUG*, which is very bad.

With these patches, bugpoint has successfully found a bug for me in a function
with several nested loops, and cut it down to just one of them. :) :)

llvm-svn: 12605