[PATCH] Allow users to specify NULL like macros to be replaced

[Tareq A. Siraj]

  Dmitry: Initially I thought about detecting NULL-like user macros but it becomes complicated when the user macro has side effects (most of them will) and some pre-processor magic. In this case there were too many false positives. While I do agree that suggesting NULL-like macros in some sort of diagnostic will be a good idea, the 2nd phase will still require this method. We can discuss this in details in the mailing list if you want. Thanks.

http://llvm-reviews.chandlerc.com/D574