[OPENMP]Fix threadid in __kmpc_omp_taskwait call for dependent target calls.

Summary:
We used to call __kmpc_omp_taskwait function with global threadid set to
0. It may crash the application at the runtime if the thread executing
 target region is not a master thread.

Reviewers: grokos, kkwli0

Subscribers: guansong, jdoerfert, caomhin, openmp-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D64571

llvm-svn: 366220