Upgrade to tzdata2013b.

From the release notes:

  Changes affecting current and future time stamps:

    Haiti uses US daylight-saving rules this year, and presumably future years.
    This changes time stamps starting today.  (Thanks to Steffen Thorsen.)

    Paraguay will end DST on March 24 this year.
    (Thanks to Steffen Thorsen.)  For now, assume it's just this year.

    Morocco does not observe DST during Ramadan;
    try to predict Ramadan in Morocco as best we can.
    (Thanks to Erik Homoet for the heads-up.)

Change-Id: I98d5290ea5a1d9fb1eeddab1c9e72135dc9e4bd1