[openacc] Factor out async argument utility functions

2018-05-09  Tom de Vries  <tom@codesourcery.com>

	PR libgomp/83792
	* oacc-int.h (async_valid_stream_id_p, async_valid_p)
	(async_synchronous_p): New function.
	* oacc-async.c (acc_async_test, acc_wait, acc_wait_all_async): Use
	async_valid_p.
	* oacc-cuda.c (acc_get_cuda_stream, acc_set_cuda_stream): Use
	async_valid_stream_id_p.
	* oacc-mem.c (gomp_acc_remove_pointer): Use async_synchronous_p.
	* oacc-parallel.c (GOACC_parallel_keyed): Same.

From-SVN: r260081
diff --git a/libgomp/oacc-parallel.c b/libgomp/oacc-parallel.c
index a71b399..cfba581 100644
--- a/libgomp/oacc-parallel.c
+++ b/libgomp/oacc-parallel.c
@@ -183,7 +183,7 @@
 			      async, dims, tgt);
 
   /* If running synchronously, unmap immediately.  */
-  if (async < acc_async_noval)
+  if (async_synchronous_p (async))
     gomp_unmap_vars (tgt, true);
   else
     tgt->device_descr->openacc.register_async_cleanup_func (tgt, async);