Revert "[ObjC] Make C++ triviality type traits available to non-trivial C"

This reverts commit r329289.

It was decided that we shouldn't expose the __has_* traits to C since
they are deprecated and useless.

See the discussion here:

http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180402/thread.html#223921

llvm-svn: 329608