[vala] gobject-2.0: Fix bootstrap build with valac < 0.26

[Rico Tzschichholz <ricotz src gnome org>]

commit 9e6c0554e2a6cc4ce07ddb71d2a5dc4edd4a56e6
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Feb 16 12:00:27 2017 +0100

    gobject-2.0: Fix bootstrap build with valac < 0.26

 vapi/gobject-2.0.vapi |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/vapi/gobject-2.0.vapi b/vapi/gobject-2.0.vapi
index a16c6d7..db01748 100644
--- a/vapi/gobject-2.0.vapi
+++ b/vapi/gobject-2.0.vapi
@@ -327,7 +327,11 @@ namespace GLib {
                public ParamSpecPool (bool type_prefixing = false);
                public void insert (GLib.ParamSpec pspec, GLib.Type owner_type);
                [CCode (array_length_pos = 1.1, array_length_type = "guint")]
+#if VALA_0_26
                public (unowned GLib.ParamSpec)[] list (GLib.Type owner_type);
+#else
+               public unowned GLib.ParamSpec[] list (GLib.Type owner_type);
+#endif
                public GLib.List<weak GLib.ParamSpec> list_owned (GLib.Type owner_type);
                public unowned GLib.ParamSpec lookup (string param_name, GLib.Type owner_type, bool 
walk_ancestors);
                public void remove (GLib.ParamSpec pspec);