[vala/staging] gtk+-3.0: Update to 3.22.30+21fddc39

[Rico Tzschichholz <ricotz src gnome org>]

commit d720fdfed18a924c6c0c48666afcdde60e6925af
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sun Apr 22 15:32:44 2018 +0200

    gtk+-3.0: Update to 3.22.30+21fddc39

 vapi/gtk+-3.0.vapi |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/vapi/gtk+-3.0.vapi b/vapi/gtk+-3.0.vapi
index 2037f31..2d63d68 100644
--- a/vapi/gtk+-3.0.vapi
+++ b/vapi/gtk+-3.0.vapi
@@ -4767,7 +4767,7 @@ namespace Gtk {
                [Version (deprecated = true, deprecated_since = "3.10")]
                public void set_tearoff_state (bool torn_off);
                [Version (deprecated = true, deprecated_since = "3.10")]
-               public void set_title (string title);
+               public void set_title (string? title);
                [Version (since = "2.14")]
                public Gtk.AccelGroup accel_group { get; set; }
                [Version (since = "2.14")]