[PATCH] Fix a PassManager pointer use-after-free bug

[Chandler Carruth]

  Blast from the past. I was clearing out my backlog and found this.

  At this point, the work to replace the pass manager is under way, and the on-the-fly function pass support inside of a module pass has never really been thoroughly tested IMO, so I don't know if its worth trying to get this into the tree.

  Please ping the patch if you really need support for this, and add me back as a reviewer.

  Sorry for the silence on this one!

http://llvm-reviews.chandlerc.com/D154