[nvptx] Re-add removed struct parallel comment

2018-03-23  Tom de Vries  <tom@codesourcery.com>

	* config/nvptx/nvptx.c (struct parallel): Re-add comment.

---
 gcc/config/nvptx/nvptx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index 50d7319..9873449 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -2831,6 +2831,9 @@ struct offload_attrs
   int max_workers;
 };
 
+/* Loop structure of the function.  The entire function is described as
+   a NULL loop.  */
+
 struct parallel
 {
   /* Parent parallel.  */