Issue #10827: Changed the rules for 2-digit years. The time.asctime

Issue #10827: Changed the rules for 2-digit years.  The time.asctime
function will now format any year when time.accept2dyear is false and
will accept years >= 1000 otherwise.  The year range accepted by
time.mktime and time.strftime is still system dependent, but
time.mktime will now accept full range supported by the OS. Conversion
of 2-digit years to 4-digit is deprecated.