Update submodules: util (new commits)

util:
    93594b6 Chris Smith <chris@dmdirc.com>
            Remove pointless method.

            Sockets are closeable now. Woo.

            Gerrit: http://gerrit.dmdirc.com/4065

Change-Id: Ia0d62bc7d36c3b7f7ed1abd27eab5292a33f2fe4