arm_acle: Implement swap intrinsic

Insert the LDREX/STREX instruction sequence specified in ARM ACLE 2.0,
as SWP instruction is deprecated since ARMv6.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@216446 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan/Win] Add an extra thunk.lib to handle stack-use-after-return option

With this patch, "check-asan" passes all the tests with both MT and MD ASan RTL if you set COMPILER_RT_BUILD_SHARED_ASAN to ON
(PR20214)

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@216447 91177308-0d34-0410-b5e6-96231b3b80d8