Fix freeing of GOMP stream.

stream->nr_unregistered_views must be set to 0 at creation to ensure
destruction works correctly.

libgomp/stream.c

@@ -96,6 +96,7 @@ GOMP_stream_create_stream (size_t element_size, size_t buffer_size)
   stream->connected_p = false;
   stream->eos_p = false;
   stream->pre_shift = 0;
+  stream->unregistered_views = 0;
 
   /* Initialize the view_handles.  */
   stream->read_views.current_min = stream->buffer_size;