[PATCH] Add diagnostic capabilities in LLVM (frontend part)

[Quentin Colombet]

  Thanks!

  Committed in r200931.

  I’ve filed http://llvm.org/bugs/show_bug.cgi?id=18759 to keep track of the missing demangling in the diagnostic.
  http://llvm.org/bugs/show_bug.cgi?id=4072 already keep track of the progress on the frame-larger-than warning and I particular I plan to track there the progress to remove the need of the backend switch.

  -Quentin

http://llvm-reviews.chandlerc.com/D2430