[cogl] egl: don't bind the wayland display if the extension is not available

[Neil Roberts <nroberts src gnome org>]

commit 8d4e4b0e8062708cece4d4c929abccc492ee21cc
Author: Giovanni Campagna <gcampagn redhat com>
Date:   Tue Jul 23 17:10:57 2013 +0200

    egl: don't bind the wayland display if the extension is not available
    
    When running in a purely swrast environment (such as with
    LIBGL_ALWAYS_SOFTWARE), the extension is not exposed by mesa,
    but wayland is still possible with wl_shm.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=704750
    
    Reviewed-by: Neil Roberts <neil linux intel com>

 cogl/winsys/cogl-winsys-egl.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/cogl/winsys/cogl-winsys-egl.c b/cogl/winsys/cogl-winsys-egl.c
index e5aa7e8..18d2649 100644
--- a/cogl/winsys/cogl-winsys-egl.c
+++ b/cogl/winsys/cogl-winsys-egl.c
@@ -455,8 +455,9 @@ _cogl_winsys_display_setup (CoglDisplay *display,
       struct wl_display *wayland_display = display->wayland_compositor_display;
       CoglRendererEGL *egl_renderer = display->renderer->winsys;
 
-      egl_renderer->pf_eglBindWaylandDisplay (egl_renderer->edpy,
-                                              wayland_display);
+      if (egl_renderer->pf_eglBindWaylandDisplay)
+       egl_renderer->pf_eglBindWaylandDisplay (egl_renderer->edpy,
+                                               wayland_display);
     }
 #endif