shared: FORMAT_TIMESTAMP_MAX -- include space for unicode weekdays

shared: FORMAT_TIMESTAMP_MAX -- include space for unicode weekdays

$ LANG=el_GR.UTF-8 ./timedatectl
      Local time: Σαβ 2012-11-24 14:53:05 CET
  Universal time: Σαβ 2012-11-24 13:53:05 UTC
        RTC time: Σαβ 2012-11-24 13:53:04
        Timezone: Europe/Berlin (CET, +0100)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: no
 Last DST change: DST ended at
                  Κυρ 2012-10-28 02:59:59 CEST
                  Κυρ 2012-10-28 02:00:00 CET
 Next DST change: DST begins (the clock jumps one hour forward) at
                  Κυρ 2013-03-31 01:59:59 CET
                  Κυρ 2013-03-31 03:00:00 CEST

https://bugs.freedesktop.org/show_bug.cgi?id=57470