pgsql: Update timezone code to track the upstream changes since 2003.

Log Message:
-----------
Update timezone code to track the upstream changes since 2003. In particular
this adds support for 64-bit tzdata files, which is needed to support DST
calculations beyond 2038. Add a regression test case to give some minimal
confidence that that really works.

Heikki Linnakangas

Modified Files:
--------------
pgsql/src/test/regress/expected:
timestamptz.out (r1.28 -> r1.29)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/timestamptz.out?r1=1.28&r2=1.29)
pgsql/src/test/regress/sql:
timestamptz.sql (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/timestamptz.sql?r1=1.16&r2=1.17)
pgsql/src/timezone:
README (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/README?r1=1.5&r2=1.6)
ialloc.c (r1.9 -> r1.10)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/ialloc.c?r1=1.9&r2=1.10)
localtime.c (r1.19 -> r1.20)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/localtime.c?r1=1.19&r2=1.20)
pgtz.c (r1.58 -> r1.59)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/pgtz.c?r1=1.58&r2=1.59)
pgtz.h (r1.21 -> r1.22)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/pgtz.h?r1=1.21&r2=1.22)
private.h (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/private.h?r1=1.11&r2=1.12)
scheck.c (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/scheck.c?r1=1.8&r2=1.9)
strftime.c (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/strftime.c?r1=1.11&r2=1.12)
tzfile.h (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/tzfile.h?r1=1.6&r2=1.7)
zic.c (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/timezone/zic.c?r1=1.22&r2=1.23)