[vala-extra-vapis] fix memory corruptions

[Evan Nemerson <evann src gnome org>]

commit 30468aae6e47ecf87e04e92db063dfd20314388b
Author: Fabrice Thiroux <fabrice thiroux free fr>
Date:   Sun Apr 24 12:24:42 2016 +0200

    fix memory corruptions

 libmarkdown.vapi |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/libmarkdown.vapi b/libmarkdown.vapi
index 09268ab..25e2483 100644
--- a/libmarkdown.vapi
+++ b/libmarkdown.vapi
@@ -69,13 +69,13 @@ namespace Markdown
                public static void string_to_anchor<T> (uint8[] buffer, StringToAnchorCallback<T> sta, T 
@out, DocumentFlags flags);
                public int xhtmlpage (DocumentFlags flags, GLib.FileStream file);
 
-               public string doc_title ();
-               public string doc_author ();
-               public string doc_date ();
+               public unowned string doc_title ();
+               public unowned string doc_author ();
+               public unowned string doc_date ();
 
                public int document (out unowned string text);
-               public int toc (out string @out);
-               public int css (out string @out);
+               public int toc (out unowned string @out);
+               public int css (out unowned string @out);
                public static int xml (uint8[] buffer, out string @out);
 
                public int generatehtml (GLib.FileStream file);