[gnome-control-center] build: Bump minimum GTK+ version to 3.19.12

[Debarshi Ray <debarshir src gnome org>]

commit 816c6990cf8049c9e53c4d7619ff93c84e2b1c64
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Mar 14 19:28:53 2016 +0100

    build: Bump minimum GTK+ version to 3.19.12
    
    We rely on the latest changes to GtkWindow's size handling logic.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=762548

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index debc9c9..16407aa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,7 +86,7 @@ dnl Check that we meet the  dependencies
 dnl ==============================================
 
 GLIB_REQUIRED_VERSION=2.44.0
-GTK_REQUIRED_VERSION=3.15.0
+GTK_REQUIRED_VERSION=3.19.12
 PA_REQUIRED_VERSION=2.0
 CANBERRA_REQUIRED_VERSION=0.13
 GDKPIXBUF_REQUIRED_VERSION=2.23.0