[mutter] configure: Actually make gbm optional

[Jasper St. Pierre <jstpierre src gnome org>]

commit 60cbb41f4237e1bf53cdf95ef5a8aef449ad1797
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Wed Oct 15 11:13:21 2014 -0700

    configure: Actually make gbm optional
    
    Whoops, I made the code work without it, but forgot to strip it from the
    actual list of requires packages.
    
    Spotted-by: Rico Tzschichholz <ricotz ubuntu com>

 configure.ac |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f238972..25d822a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -78,7 +78,6 @@ MUTTER_PC_MODULES="
    gsettings-desktop-schemas >= 3.7.3
    $CLUTTER_PACKAGE >= 1.19.5
    cogl-1.0 >= 1.17.1
-   gbm >= 10.3
    upower-glib >= 0.99.0
    gnome-desktop-3.0
    xcomposite >= 0.2