* editfns.c: (TM_YEAR_BASE): Move up.

* editfns.c: (TM_YEAR_BASE): Move up.
(Fdecode_time, Fencode_time): Use TM_YEAR_BASE instead of 1900.
(Fdecode_time): Cast tm_year to EMACS_INT, to avoid overflow when
int is narrower than EMACS_INT.
(Fcurrent_time_string): As with Fformat_time_string, report an
invalid time specification if the argument is invalid.  Also,
check for out-of-range time stamps.