[PATCH] Add CreatePointerBitCastOrAddrSpaceCast to IRBuilder and co.

[Matt Arsenault]

  It's also more restrictive in that it doesn't allow ptrtoints.  This has the same problem that I mentioned in D2205 when I added the constant version. The ptrtoint handling in CreatePointerCast would make using this in CreatePointerCast messy.

http://llvm-reviews.chandlerc.com/D2598