[libgit2-glib] Bump libgit2 requirement to 0.21

[Ignacio Casal Quinteiro <icq src gnome org>]

commit aa03a290fefdbcd25b071df6934e36a83b181345
Author: Ignacio Casal Quinteiro <icq gnome org>
Date:   Sun Jun 22 15:33:47 2014 +0200

    Bump libgit2 requirement to 0.21

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 629770d..9f69dcd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -56,7 +56,7 @@ GTK_DOC_CHECK([1.11], [--flavour=no-tmpl])
 
 INTROSPECTION_REQUIRED=0.10.1
 GLIB_REQUIRED=2.28.0
-GIT2_REQUIRED=0.20.0
+GIT2_REQUIRED=0.21.0
 
 PKG_CHECK_MODULES(LIBGIT2_GLIB, [
        gobject-2.0 >= $GLIB_REQUIRED