new time zone code and data files

The files ftp://elsie.nci.nih.gov/~pub/tzcode1997g.tar.gz and ftp://elsie.nci.nih.gov/~pub/tzdata1997h.tar.gz are now available. These files incorporate the corrections for Uruguay (and other locations) that were sent to the time zone mailing list last week; they also incorporate your correspondent's simple-minded fix allowing mktime to both correctly handle leap seconds and correctly handle tm_sec values upon which arithmetic has been performed. (A ponder of Tom Peterson's suggested optimizations to those changes is in my queue.) --ado