[boost] [date_time] Eliminate pre-1.33.0 io facet code?

Subject: [boost] [date_time] Eliminate pre-1.33.0 io facet code?
From: James E. King, III (jking_at_[hidden])
Date: 2018-01-06 16:45:12

There was a bug change around the 1.33.0 release timeframe that added new
io facet handling for date_time.  It is conditionally disabled using the
definition USE_DATE_TIME_PRE_1_33_FACET_IO.  I suggested in a github issue
that the pre-1.33 mode be removed at this point.  Any thoughts on that?

https://github.com/boostorg/date_time/issues/61

- Jim