Switch timeSeriesStats to use simulationStartTime

Previously, timeSeriesStats was using the start time of the current
run as the beginning of stats.  Since this time starts over at
restarts, it was not triggering a reset of the stats as it should
have at the beginning of a restart interval that is commensurate
with the time-averaging interval.

With this merge, we now use the `simulationStartTime` to determine
when time-averaging began, so that alarms are correctly triggered
on restart.

components/mpas-ocean/src/analysis_members/mpas_ocn_time_series_stats.F

@@ -23,6 +23,7 @@ module ocn_time_series_stats
   use mpas_stream_manager
 
   use ocn_constants
+  use ocn_diagnostics_variables
 
   implicit none
   private
@@ -262,13 +263,7 @@ subroutine ocn_init_time_series_stats(domain, instance, err)!{{{
 
   ! set xtime start if it is still unset, for very first time step
   ! (i.e., no restarts)
-  start_time = mpas_get_clock_time(domain%clock, MPAS_START_TIME, err_tmp)
-  call mpas_get_time(start_time, dateTimeString=start_xtime, ierr=err_tmp)
-  if (err_tmp /= 0) then
-     call mpas_log_write('Error getting start time in init', &
-          MPAS_LOG_ERR, masterOnly=.true., flushNow=.true.)
-     err = ior(err, err_tmp)
-  endif
+  start_xtime = simulationStartTime
 
   call mpas_pool_get_config(domain % configs, 'config_output_reference_time', &
     config_output_reference_time)
@@ -1813,8 +1808,8 @@ subroutine set_times(series, alarms, clock, which, config, ok, err)
     ! set the time
     if (which == START_TIMES) then
       if (time == INITIAL_TIME_TOKEN) then
-        alarms(b) % start_time = &
-          mpas_get_clock_time(clock, MPAS_START_TIME, err)
+        call mpas_set_time(alarms(b) % start_time, &
+          dateTimeString=simulationStartTime)
       else
         call mpas_set_time(alarms(b) % start_time, &
           dateTimeString=time, ierr=err)