Bug 1031529 part 1 - Add a --no-threads shell flag. r=bhackett
Bug 1031529 part 2 - Remove JS_THREADSAFE #ifdefs everywhere. r=bhackett
Bug 1031529 part 3 - Step defining JS_THREADSAFE, remove --disable-threadsafe. r=glandium
Bug 1031529 part 4 - Remove getBuildConfiguration().threadsafe. r=bhackett