[gtk+] Bump the Graphene dependency

[Emmanuele Bassi <ebassi src gnome org>]

commit 7ae83717afda072adf89522616ef22c72611f29d
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Nov 21 16:24:34 2016 +0000

    Bump the Graphene dependency
    
    The initialization macros for Point, Point3D, Size, and Rectangle have
    been modified in Graphene 1.5.1 to allow their use as compound
    literals.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 09c53d0..6e337ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -64,7 +64,7 @@ m4_define([wayland_protocols_required_version], [1.7])
 m4_define([mirclient_required_version], [0.22.0])
 m4_define([mircookie_required_version], [0.17.0])
 m4_define([epoxy_required_version], [1.0])
-m4_define([graphene_required_version], [1.2])
+m4_define([graphene_required_version], [1.5.1])
 GLIB_REQUIRED_VERSION=glib_required_version
 PANGO_REQUIRED_VERSION=pango_required_version
 ATK_REQUIRED_VERSION=atk_required_version