Make yeartot() declaration match prototype.
Add tests for PR lib/47916.  Some of these fail.
A time like HH:MM:SS.sss says nothing about whether DST is on or off.
Add a new non-terminal "time_numericzone" for a time with
a numeric timezone.  Move some productions from "time" to "time_numericzone".
Increment yyHaveZone when encountering one of these.

Previously, input of the form "HH:MM:SS +ZZZZ" would not have set the
yyhaveZone flag.