Fixing implementation of bittestandset in Intrin.h.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191783 91177308-0d34-0410-b5e6-96231b3b80d8
Revert commits r190613, r190560 and r190557.

The added a cmake invocation to null builds, making them a lot slower.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191784 91177308-0d34-0410-b5e6-96231b3b80d8