[mutter] background-actor: Add missing paren

[Jasper St. Pierre <jstpierre src gnome org>]

commit 7e0822c5b194fd4a7c20efd8ddb14ff47f3aa113
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Fri Sep 5 13:51:21 2014 -0700

    background-actor: Add missing paren

 src/compositor/meta-background-actor.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/compositor/meta-background-actor.c b/src/compositor/meta-background-actor.c
index 4d4651b..3118608 100644
--- a/src/compositor/meta-background-actor.c
+++ b/src/compositor/meta-background-actor.c
@@ -329,7 +329,7 @@ setup_pipeline (MetaBackgroundActor   *self,
         {
           /* Darken everything to match the average brightness that would
            * be there if we were drawing the vignette, which is
-           * (1 - (pi/12.) * vignette_sharpness [exercise for the reader :]
+           * (1 - (pi/12.) * vignette_sharpness) [exercise for the reader :]
            */
           color_component *= (1 - 0.74 * priv->vignette_sharpness);
         }