dix: Fix up colormap fixup.

FindClientResourcesByType() will walk all colormaps on all screens; we
only want to fix up the current screen.  Otherwise, screens > 0 will
have the visual pointers for their colormaps pointing off into space.

Signed-off-by: Adam Jackson <ajax@redhat.com>
(cherry picked from commit 15b30fde17)

dix/colormap.c

@@ -2705,6 +2705,9 @@ static void _colormap_find_resource(pointer value, XID id,
     ColormapPtr cmap = value;
     int j;
 
+    if (pScreen != cmap->pScreen)
+	return;
+
     j = cmap->pVisual - pScreen->visuals;
     cmap->pVisual = &visuals[j];
 }