[PATCH] Workaround some MSan bootstrap issues.

[Kostya Serebryany]

  >> Weird. I removed this stack allocation code, and still no leak report from Valgrind.
  I suspect that that code was added for some special flavor of linux, where Valgrind misbehaved.

  I'd certainly prefer to remove this code and fix the problem (if it still exist) on the Valgrind side,
  but I think we should let chapuni@ defend his change.

http://llvm-reviews.chandlerc.com/D402