[dovecot/core] ffd8dc: master: Add master socket's io listener later.

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: ffd8dc932516bc55bf01d91355540daab365e5e9
      https://github.com/dovecot/core/commit/ffd8dc932516bc55bf01d91355540daab365e5e9
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2016-07-04 (Mon, 04 Jul 2016)

  Changed paths:
    M src/master/service-listen.c
    M src/master/service-monitor.c

  Log Message:
  -----------
  master: Add master socket's io listener later.

Most importantly this fixes startup failure with kqueue:

Panic: kevent(EV_ADD, READ, 56) failed: Bad file descriptor

kqueue doesn't survive a fork(), so this change delays its creation until
after fork().