(PHP 5.5.0, PECL >= 3.0.0a1)
IntlCalendar::setRepeatedWallTimeOption — Set behavior for handling repeating wall times at negative timezone offset transitions
$wallTimeOption
   )
   Sets the current strategy for dealing with wall times that are repeated
   whenever the clock is set back during dailight saving time end transitions.
   The default value is IntlCalendar::WALLTIME_LAST (take
   the post-DST instant). The other possible value is
   IntlCalendar::WALLTIME_FIRST (take the instant that
   occurs during DST).
  
wallTimeOption
    
      One of the constants IntlCalendar::WALLTIME_FIRST or
      IntlCalendar::WALLTIME_LAST.
     
   Returns TRUE on success. Failure can only happen due to invalid parameters.
  
See the example on IntlCalendar::getRepeatedWallTimeOption().