[dovecot/core] cbe628: Compiler warning fix

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: cbe62867ab24435145aeb6c098141f07d8c9ab5c
      https://github.com/dovecot/core/commit/cbe62867ab24435145aeb6c098141f07d8c9ab5c
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2016-07-06 (Wed, 06 Jul 2016)

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

  Log Message:
  -----------
  Compiler warning fix