postgres/src/timezone

This is a PostgreSQL adapted version of the timezone library
from:

	ftp://elsie.nci.nih.gov/pub/tz*.tar.gz

The interface is used when USE_PGTZ is defined at the top level. This
will cause the following functions to be redefined:
  localtime		pg_localtime
  gmtime		pg_gmtime
  asctime		pg_asctime
  ctime			pg_ctime
  difftime		pg_difftime
  mktime		pg_mktime
  tzset			pg_tzset

and the TIMEZONE_GLOBAL define in c.h is redefined to pg_timezone.