[PATCH] Interception macros for sanitizers on FreeBSD

[Kostya Serebryany]

  So, this change only adds ifdef __FreeBSD__ in a few places and renames a few files/macros.
  Maybe we could avoid the renaming too?
  Just add defined(def __FreeBSD__ ) where needed?

http://llvm-reviews.chandlerc.com/D2828