[seahorse] Fix some return_(val_)_if_fail mismatches

[Ryan Lortie <desrt src gnome org>]

commit 395a5ef1290a1abc9d2a733a64f580465629dffb
Author: Ryan Lortie <desrt desrt ca>
Date:   Tue Jan 14 23:52:32 2014 -0500

    Fix some return_(val_)_if_fail mismatches
    
    https://bugzilla.gnome.org/show_bug.cgi?id=722023

 gkr/gkr-backend.vala |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/gkr/gkr-backend.vala b/gkr/gkr-backend.vala
index 7caed01..66647a9 100644
--- a/gkr/gkr-backend.vala
+++ b/gkr/gkr-backend.vala
@@ -62,7 +62,7 @@ public class Backend: GLib.Object , Gcr.Collection, Seahorse.Backend {
        private Gtk.ActionGroup _actions;
 
        construct {
-               return_if_fail(_instance == null);
+               return_val_if_fail(_instance == null, null);
                Backend._instance = this;
 
                this._actions = BackendActions.instance(this);
@@ -146,13 +146,13 @@ public class Backend: GLib.Object , Gcr.Collection, Seahorse.Backend {
        }
 
        public static void initialize() {
-               return_val_if_fail(Backend._instance == null, null);
+               return_if_fail(Backend._instance == null);
                (new Backend()).register();
                return_if_fail(Backend._instance != null);
        }
 
        public static Backend instance() {
-               return_if_fail(Backend._instance != null);
+               return_val_if_fail(Backend._instance != null, null);
                return Backend._instance;
        }