[dovecot/core] df8b4f: lib-index: Fix compiler warning with 32bit time_t

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: df8b4fbe4287c0830aaa67d17a76bc6554725976
      https://github.com/dovecot/core/commit/df8b4fbe4287c0830aaa67d17a76bc6554725976
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2017-07-12 (Wed, 12 Jul 2017)

  Changed paths:
    M src/lib-index/mail-transaction-log.c

  Log Message:
  -----------
  lib-index: Fix compiler warning with 32bit time_t