Pre-1970 dates causes `OverflowError` ("can't convert negative int to unsigned")

[fdcastel]

Trying to pass datetime.date(1727, 4, 1) as a SQL DATE parameter causes this line of Cursor._pack_input() to raise a OverflowError("can't convert negative int to unsigned")

_util.encode_date(value) returns -48077 in this case.