[gnome-shell] Require clutter-1.0 >= 1.21.5

[Rico Tzschichholz <ricotz src gnome org>]

commit 4660015bb1913e530dcb2a25db9e671e629436ae
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Mon Feb 23 22:05:16 2015 +0100

    Require clutter-1.0 >= 1.21.5
    
    Needed for clutter_actor_set_opacity_override which usage was
    introduced by 07664e7d2f5bcc97fd137fd4a228be54046fe5a9

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index e729666..ca903ae 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,7 +73,7 @@ AS_IF([test x$enable_systemd != xno], [
 
 AC_MSG_RESULT($enable_systemd)
 
-CLUTTER_MIN_VERSION=1.15.90
+CLUTTER_MIN_VERSION=1.21.5
 GOBJECT_INTROSPECTION_MIN_VERSION=0.10.1
 GJS_MIN_VERSION=1.39.0
 MUTTER_MIN_VERSION=3.15.90