[dovecot/core] 778529: dsync: fix splitting login from host

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: 7785296a7f51d88c0a0be15f6ac60c0c43a30a79
      https://github.com/dovecot/core/commit/7785296a7f51d88c0a0be15f6ac60c0c43a30a79
  Author: Thomas Reifferscheid <thomas at reifferscheid.org>
  Date:   2017-07-04 (Tue, 04 Jul 2017)

  Changed paths:
    M src/doveadm/doveadm-dsync.c

  Log Message:
  -----------
  dsync: fix splitting login from host

Using strchr() was splitting login and host at the first
occurrence of '@' which leads to troublesome behaviour.
When calling strace one would notice the misbehaviour:

execve("/usr/sbin/ssh", ["ssh", "-lthomas", "domain.org at 10.8.13.2"

using strrch() however splits login and host at the last occurrence
of '@'.

Signed-off-by: Thomas Reifferscheid <thomas at reifferscheid.org>