[PATCH] Disable branch folding with MemorySanitizer

[Renato Golin]

  I do like the idea of having better debug experience at -O1 (which is almost never used for anything else), but I also agree this is a bit too low to implement such change.

  I was expecting some compiler flag that would be false by default, but true with sanitizers, and that would disable a whole pass, not just part of one.

  I don't think skipping the whole SimplifyCFG would be unreasonable for debugging experience purposes.

http://llvm-reviews.chandlerc.com/D2214