[gegl/mrg_ui] gegl-binary: do not link mrg_ui_main when mrg isnt available

[Øyvind Kolås <ok src gnome org>]

commit 55918b8d1fbecb5aee42f78141e55ba280d9b22c
Author: Oyvind Kolas <pippin gimp org>
Date:   Wed Jul 29 00:14:23 2015 +0200

    gegl-binary: do not link mrg_ui_main when mrg isnt available

 bin/gegl.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/bin/gegl.c b/bin/gegl.c
index b2fe155..d92d946 100644
--- a/bin/gegl.c
+++ b/bin/gegl.c
@@ -176,8 +176,10 @@ main (gint    argc,
   
   if (o->mode == GEGL_RUN_MODE_DISPLAY)
     {
+#if HAVE_MRG
       mrg_ui_main (argc, argv);
       return 0;
+#endif
     }
 
   gegl = gegl_node_new_from_xml (script, path_root);