rc.lua: Use the new client API for the titlebar buttons.

awesomerc.lua

@@ -527,7 +527,7 @@ end)
 -- Add a titlebar if titlebars_enabled is set to true in the rules.
 client.connect_signal("request::titlebars", function(c)
     -- buttons for the titlebar
-    local buttons = gears.table.join(
+    local buttons = {
         awful.button({ }, 1, function()
             c:emit_signal("request::activate", "titlebar", {raise = true})
             awful.mouse.client.move(c)
@@ -535,8 +535,8 @@ client.connect_signal("request::titlebars", function(c)
         awful.button({ }, 3, function()
             c:emit_signal("request::activate", "titlebar", {raise = true})
             awful.mouse.client.resize(c)
-        end)
-    )
+        end),
+    }
 
     awful.titlebar(c) : setup {
         { -- Left