Fix include of config.h that was incorrectly changed in r331184

The RWMutex implementation depends on config.h macros (specifically
HAVE_PTHREAD_H and HAVE_PTHREAD_RWLOCK_INIT), so we need to be
including it and not just llvm-config.h here or we fall back to a much
slower implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331487 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed