Holiday.dates always fails with tz-aware input

[ssanderson]

The conversion from start_date to base_date on https://github.com/pydata/pandas/blob/master/pandas/tseries/holiday.py#L206 drops tz information, which causes the DatetimeIndex constructor to barf if end_date is tz-aware. Fixed by #9824.

[jreback]

closed by #9824