[gtk+] Bump version to 3.91.0

[Timm Bäder <baedert src gnome org>]

commit 2ab3da6741dca3eb9ac2c26b951ccdcfb834a558
Author: Timm Bäder <mail baedert org>
Date:   Tue Apr 25 20:16:59 2017 +0200

    Bump version to 3.91.0
    
    So we can use GDK_AVAILABLE_IN_3_92 without getting warnings

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index caaae26..795f9b1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@
 # set GTK_BINARY_AGE and GTK_INTERFACE_AGE to 0.
 
 m4_define([gtk_major_version], [3])
-m4_define([gtk_minor_version], [90])
+m4_define([gtk_minor_version], [91])
 m4_define([gtk_micro_version], [0])
 m4_define([gtk_interface_age], [0])
 m4_define([gtk_binary_age],