[cogl] framebuffer: NOP _set_color_mask if mask isn't changing

[Robert Bragg <rbragg src gnome org>]

commit 925174d99df7f1f4b11098e748bcc23eaa396a21
Author: Robert Bragg <robert linux intel com>
Date:   Tue Oct 15 14:04:12 2013 +0100

    framebuffer: NOP _set_color_mask if mask isn't changing
    
    This makes cogl_framebuffer_set_color_mask immediately bail out if the
    given mask equals the framebuffer's current mask, since the cost of
    flushing the journal and flushing the gl state will hugely outweigh the
    cost of the check.
    
    Reviewed-by: Neil Roberts <neil linux intel com>

 cogl/cogl-framebuffer.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/cogl/cogl-framebuffer.c b/cogl/cogl-framebuffer.c
index b98719c..b002f61 100644
--- a/cogl/cogl-framebuffer.c
+++ b/cogl/cogl-framebuffer.c
@@ -946,6 +946,9 @@ void
 cogl_framebuffer_set_color_mask (CoglFramebuffer *framebuffer,
                                  CoglColorMask color_mask)
 {
+  if (framebuffer->color_mask == color_mask)
+    return;
+
   /* XXX: Currently color mask changes don't go through the journal */
   _cogl_framebuffer_flush_journal (framebuffer);