Fix for crash in task dependencies

[tlwilmar]

Summary

With single thread using __kmpc_omp_wait_deps segfaults in openmp runtime. Offloading with depend also encounters this problem when we generate kmpc_omp_wait_deps instead of kmpc_omp_task_with_deps.

Patch by Alex Duran

[AndreyChurbanov]

LGTM

openmp/trunk/runtime/src/kmp_taskdeps.cpp

__kmpc_omp_wait_deps ( ident_t *loc_ref, kmp_int32 gtid, kmp_int32 ndeps, kmp_depend_info_t *dep_list,
     kmp_info_t *thread = __kmp_threads[ gtid ];
     kmp_taskdata_t * current_task = thread->th.th_current_task;
 
     // We can return immediately as:
     //   - dependences are not computed in serial teams (except if we have proxy tasks)
     //   - if the dephash is not yet created it means we have nothing to wait for
     bool ignore = current_task->td_flags.team_serial || current_task->td_flags.tasking_ser || current_task->td_flags.final;
 #if OMP_45_ENABLED
-    ignore = ignore && thread->th.th_task_team->tt.tt_found_proxy_tasks == FALSE;
+    ignore = ignore && thread->th.th_task_team != NULL && thread->th.th_task_team->tt.tt_found_proxy_tasks == FALSE;
 #endif
     ignore = ignore || current_task->td_dephash == NULL;
 
     if ( ignore ) {
         KA_TRACE(10, ("__kmpc_omp_wait_deps(exit): T#%d has no blocking dependencies : loc=%p\n", gtid, loc_ref) );
         return;
     }