[vala] glib-2.0: Fix wrong return type of OptionContext.get_description()

[Rico Tzschichholz <ricotz src gnome org>]

commit 9a7b1963af282220535c7701805ea72fd6f1462c
Author: Jee-Yong Um <conr2d gmail com>
Date:   Fri Sep 9 16:14:42 2016 +0900

    glib-2.0: Fix wrong return type of OptionContext.get_description()
    
    OptionContext.get_description() should return 'unowned string', but it
    does not return any value currently. (void)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771123

 vapi/glib-2.0.vapi |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/vapi/glib-2.0.vapi b/vapi/glib-2.0.vapi
index 8e6b91d..9227cbb 100644
--- a/vapi/glib-2.0.vapi
+++ b/vapi/glib-2.0.vapi
@@ -3621,7 +3621,7 @@ namespace GLib {
                [Version (since = "2.12")]
                public void set_description (string description);
                [Version (since = "2.12")]
-               public void get_description ();
+               public unowned string get_description ();
                [Version (since = "2.12")]
                public void set_translate_func (TranslateFunc func, DestroyNotify? destroy_notify);
                [Version (since = "2.12")]