[OpenMP][FIX] Data race in the SPMD execution of the new runtime

[jdoerfert]

Summary

We need to synchronize the threads *before* we destroy the RAII objects
that hold the old values and not after to avoid threads executing the
parallel region but seeing an inconsistent state.

[tianshilei1992]

Yeah, that's the one. LGTM

openmp/libomptarget/DeviceRTL/src/Parallelism.cpp

synchronize::threads();
       state::ValueRAII ParallelTeamSizeRAII(state::ParallelTeamSize, NumThreads,
                                             1u, TId == 0);
       state::ValueRAII ActiveLevelRAII(icv::ActiveLevel, 1u, 0u, TId == 0);
       state::ValueRAII LevelRAII(icv::Level, 1u, 0u, TId == 0);
       synchronize::threads();
 
       if (TId < NumThreads)
         invokeMicrotask(TId, 0, fn, args, nargs);
-    }
       synchronize::threads();
+    }
     return;
   }
 
   // We do *not* create a new data environment because all threads in the team
   // that are active are now running this parallel region. They share the
   // TeamState, which has an increase level-var and potentially active-level
   // set, but they do not have individual ThreadStates yet. If they ever
   // modify the ICVs beyond this point a ThreadStates will be allocated.