Trap Time::Local infinite loop

Trap Time::Local infinite loop

Here's a new patch for Time::Local that dies if it detects that it is
looping:

work% perl -wle 'use Time::Local; print timegm(8, 14, 3, 19, 11, 997)'
Couldn't handle date (8, 14, 3, 19, 11, 997) at -e line 1
work%

Under Linux here, it handles all dates in the years 1970 thru 2038
(70-99, 00-38) and dies for all other years. I don't try to address
the fact that strange values are returned for dates in '38 from
February onwards: the 31-bit epoch ends at 03:14:07 19th Jan 2038.

p5p-msgid: 199710030030.BAA17372@crypt.compulink.co.uk