[vino] Fix a compiler warning, closes #590765

[Jonh Wendell <jwendell src gnome org>]

commit 112dfb1567a2b9325b7d37c6bedb63393097cab9
Author: Jonh Wendell <jwendell gnome org>
Date:   Thu Aug 6 10:53:55 2009 -0300

    Fix a compiler warning, closes #590765

 server/vino-fb.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/server/vino-fb.c b/server/vino-fb.c
index 12b6e5f..b8306c1 100644
--- a/server/vino-fb.c
+++ b/server/vino-fb.c
@@ -444,7 +444,7 @@ vino_fb_poll_screen (VinoFB *vfb)
 	screen_damaged = TRUE;
     }
   
-  vfb->priv->n_scanline = ++vfb->priv->n_scanline % N_SCANLINES;
+  vfb->priv->n_scanline = (vfb->priv->n_scanline + 1) % N_SCANLINES;
 
   if (!already_damaged && screen_damaged)
     emit_damage_notify (vfb);