13.5 Implementing BARRIER construct

  void GOMP_barrier_ext (int kind)
  void GOMP_barrier_cancel_ext (int kind)

kind should be GOMP_BARRIER_EXPLICIT. Other values are for implicit barriers resulting from parallel or work-sharing constructs.

GOMP_barrier and GOMP_barrier_cancel are kept for backward compatibility but new code only calls the _ext variants.

GOMP_barrier_cancel_ext should be used when the barrier happens within a cancellable construct.