[gnome-todo] build: Use AX_IS_RELEASE

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit f38c3611bc65a017edfc714f6f8b4630b9d8a293
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Jul 21 10:22:52 2015 +0100

    build: Use AX_IS_RELEASE
    
    Other macros will depend on it.

 configure.ac |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 9293eb5..cec2851 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,6 +11,9 @@ AM_INIT_AUTOMAKE([1.11.1 foreign -Wno-portability dist-xz no-dist-gzip tar-ustar
 AM_MAINTAINER_MODE([enable])
 AM_SILENT_RULES([yes])
 
+# Releases do not have git directories
+AX_IS_RELEASE([git-directory])
+
 dnl ***************************************************************************
 dnl Internationalization
 dnl ***************************************************************************