[gnome-tweak-tool] Revert increase in required Gtk version

[Phillip Wood <pwood src gnome org>]

commit 7e75c2ae62128fd28ad219bf4b04b55952e2ae01
Author: Phillip Wood <phillip wood dunelm org uk>
Date:   Wed Apr 29 18:56:14 2015 +0100

    Revert increase in required Gtk version
    
    6874ba8 AppChooser: Desensitize ‘Add’ button when no app is selected
    erroneously increased the required Gtk version number.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=747983

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 130ca05..fb70864 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,7 +8,7 @@ AM_PATH_PYTHON([2.6])
 GLIB_GSETTINGS
 
 DESKTOP_SCHEMAS_REQUIRED_VERSION=3.4.0
-GTK_REQUIRED_VERSION=3.14.0
+GTK_REQUIRED_VERSION=3.12.0
 PYGOBJECT_REQUIRED_VERSION=3.2.1
 
 PKG_CHECK_MODULES([GSETTINGS_DESKTOP_SCHEMAS], [gsettings-desktop-schemas >= 
$DESKTOP_SCHEMAS_REQUIRED_VERSION])