[dovecot/core] 3e6f1c: lib: Fix t_strf*time() unit tests

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: 3e6f1c0a999cc0abfc05d817dd89f39fb9337e76
      https://github.com/dovecot/core/commit/3e6f1c0a999cc0abfc05d817dd89f39fb9337e76
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2017-02-26 (Sun, 26 Feb 2017)

  Changed paths:
    M src/lib/test-time-util.c

  Log Message:
  -----------
  lib: Fix t_strf*time() unit tests

Timezone isn't part of the standard struct tm, so %z doesn't necessarily
expand as expected outside Linux.