* Open all listen sockets in daemonize(), while we still have stderr.

 * Open all listen sockets in daemonize(), while we still have stderr.
   Changed open_listen_socket_* routines to complain to stderr.  Now, any
   errors in binding to the listen sockets are much more obvious.

 * Simplified exit of parent after fork()

 * PID file will be correctly cleaned up if there is a failure in daemonize().

 * unlink the unix socket before trying to bind()
   (after we're sure we have the PID file)

-- kevin

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1623 a5681a0c-68f1-0310-ab6d-d61299d08faa