[gitg] Also look for gtk3-update-icon-cache

[Jesse van den Kieboom <jessevdk src gnome org>]

commit 7c48a6fee29119cfc2b074cfbfc253f812f33bd4
Author: Jesse van den Kieboom <jkieboom esri com>
Date:   Sun Sep 27 15:07:32 2015 +0200

    Also look for gtk3-update-icon-cache

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ca23a11..0487fd3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,7 +40,7 @@ AM_PROG_VALAC([0.20.1.23])
 
 AC_PATH_PROG(GLIB_MKENUMS, glib-mkenums)
 AC_PATH_PROG(GLIB_COMPILE_RESOURCES, glib-compile-resources)
-AC_PATH_PROG(GTK_UPDATE_ICON_CACHE, gtk-update-icon-cache)
+AC_PATH_PROGS(GTK_UPDATE_ICON_CACHE, gtk3-update-icon-cache gtk-update-icon-cache)
 
 AC_PATH_PROG(VALADOC, valadoc)