irc: update titlebar when switching channels

Signed-off-by: Slendi <slendi@socopon.com>

main.lua

@@ -74,10 +74,15 @@ end
 
 function IrcChatView:updateTitle()
     local tgt = self._current_target
+    local new_title
     if tgt and tgt ~= "*" then
-        self.title = tgt
+        new_title = tgt
     else
-        self.title = self._server_label
+        new_title = self._server_label
+    end
+    self.title = new_title
+    if self.titlebar and self.titlebar.setTitle then
+        self.titlebar:setTitle(new_title)
     end
 end