[mutter] MonitorXrandr: fix setting gamma ramps

[Giovanni Campagna <gcampagna src gnome org>]

commit 015c05fbf6c64a7e008ba483bdb1cf9a65ecae80
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sun Aug 18 11:44:45 2013 +0200

    MonitorXrandr: fix setting gamma ramps
    
    The value passed to XRRCrtcSetGamma must be allocated with
    XRRAllocGamma (because it relies on the locations of green and blue),
    otherwise garbage is sent on the wire.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706231

 src/core/monitor-xrandr.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)
---
diff --git a/src/core/monitor-xrandr.c b/src/core/monitor-xrandr.c
index ec9a6be..51e480a 100644
--- a/src/core/monitor-xrandr.c
+++ b/src/core/monitor-xrandr.c
@@ -921,14 +921,16 @@ meta_monitor_manager_xrandr_set_crtc_gamma (MetaMonitorManager *manager,
                                            unsigned short     *blue)
 {
   MetaMonitorManagerXrandr *manager_xrandr = META_MONITOR_MANAGER_XRANDR (manager);
-  XRRCrtcGamma gamma;
+  XRRCrtcGamma *gamma;
+
+  gamma = XRRAllocGamma (size);
+  memcpy (gamma->red, red, sizeof (unsigned short) * size);
+  memcpy (gamma->green, green, sizeof (unsigned short) * size);
+  memcpy (gamma->blue, blue, sizeof (unsigned short) * size);
 
-  gamma.size = size;
-  gamma.red = red;
-  gamma.green = green;
-  gamma.blue = blue;
+  XRRSetCrtcGamma (manager_xrandr->xdisplay, (XID)crtc->crtc_id, gamma);
 
-  XRRSetCrtcGamma (manager_xrandr->xdisplay, (XID)crtc->crtc_id, &gamma);
+  XRRFreeGamma (gamma);
 }
 
 static gboolean