o Minor bugfixes (option parsing):
    - Count unix sockets when counting client listeners (SOCKS, Trans,
      NATD, and DNS). This has no user-visible behaviour changes: these
      options are set once, and never read.
      Required for correct behaviour in ticket 17178.
      Fixes bug 19677; bugfix on 0.2.6.3-alpha.  Patch by teor.