Objective-C. Check for integer overflow in Objective-C's
boxed expression. // rdar://16417427


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211215 91177308-0d34-0410-b5e6-96231b3b80d8
CodeGen: improve ms instrincics support

Add support for _InterlockedCompareExchangePointer, _InterlockExchangePointer,
_InterlockExchange.  These are available as a compiler intrinsic on ARM and x86.
These are used directly by the Windows SDK headers without use of the intrin
header.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211216 91177308-0d34-0410-b5e6-96231b3b80d8