[mutter] Bump version to 3.17.91

[Florian Müllner <fmuellner src gnome org>]

commit 36eee04a2131b247adb383de9b3a802ac164c8d3
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Sep 3 15:26:03 2015 +0200

    Bump version to 3.17.91
    
    Update NEWS.

 NEWS         |   11 +++++++++++
 configure.ac |    2 +-
 2 files changed, 12 insertions(+), 1 deletions(-)
---
diff --git a/NEWS b/NEWS
index 2428bf5..1d7225b 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,14 @@
+3.17.91
+=======
+* Send error on pointer-gesture protocol version mismatch [Jonas; #753855]
+* Misc. cleanups [Jonas; #744932]
+
+Contributors:
+  Jonas Ådahl
+
+Translations:
+  Chao-Hsiung Liao [zh_TW], Piotr Drąg [pl]
+
 3.17.90
 =======
 * Fix glitch with some fullscreen apps [Rui; #753020]
diff --git a/configure.ac b/configure.ac
index 80d2278..2f07b35 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@ AC_PREREQ(2.62)
 
 m4_define([mutter_major_version], [3])
 m4_define([mutter_minor_version], [17])
-m4_define([mutter_micro_version], [90])
+m4_define([mutter_micro_version], [91])
 
 m4_define([mutter_version],
           [mutter_major_version.mutter_minor_version.mutter_micro_version])