[mutter] configure: Add x11-xcb to required packages

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

commit 1b596a114d2956701b99bee002aff9cbdf491504
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Thu Aug 21 10:12:07 2014 -0400

    configure: Add x11-xcb to required packages
    
    We need to link against this library now because we're using
    XGetXCBConnection. Whoops.

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 268cef8..d106a91 100644
--- a/configure.ac
+++ b/configure.ac
@@ -87,6 +87,7 @@ MUTTER_PC_MODULES="
    xkbfile
    xkeyboard-config
    xkbcommon-x11
+   x11-xcb
    xcb-randr
 "