[gnome-builder] vala: fix compilation of vala plugin

[Christian Hergert <chergert src gnome org>]

commit 28d1e39a974871be435667b6706b7db04d617136
Author: Christian Hergert <chergert redhat com>
Date:   Fri Mar 31 10:40:09 2017 -0600

    vala: fix compilation of vala plugin
    
    Vala seems to require that all interface methods are implemented, even
    though the base interface perfectly implements a default implementation.

 plugins/vala-pack/ide-vala-symbol-resolver.vala |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/plugins/vala-pack/ide-vala-symbol-resolver.vala b/plugins/vala-pack/ide-vala-symbol-resolver.vala
index 6f8501e..621e480 100644
--- a/plugins/vala-pack/ide-vala-symbol-resolver.vala
+++ b/plugins/vala-pack/ide-vala-symbol-resolver.vala
@@ -111,6 +111,13 @@ namespace Ide
                }
 
                public void load () {}
+
+               public async GLib.GenericArray<weak Ide.SourceRange> find_references_async 
(Ide.SourceLocation location,
+                                                                                           GLib.Cancellable? 
cancellable)
+                       throws GLib.Error
+               {
+                       return new GLib.GenericArray<weak Ide.SourceRange> ();
+               }
        }
 }