[libgit2-glib] Allow to enable debug builds

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

commit 5cd3b1dde07c9dc1c2d235fb33a27c45658730da
Author: Jesse van den Kieboom <jessevdk gnome org>
Date:   Fri Jul 31 20:52:40 2015 +0200

    Allow to enable debug builds

 configure.ac |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index e12456b..26323e5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,6 +40,8 @@ AM_MAINTAINER_MODE([enable])
 
 AM_SILENT_RULES([yes])
 
+AX_CHECK_ENABLE_DEBUG([no])
+
 # Initialize libtool
 LT_PREREQ([2.2])
 LT_INIT([disable-static])