pgsql: Add pg_upgrade to /contrib; will be in 9.0 beta2.

Log Message:
-----------
Add pg_upgrade to /contrib; will be in 9.0 beta2.

Add documentation.

Supports migration from PG 8.3 and 8.4.

Modified Files:
--------------
pgsql/doc/src/sgml:
contrib.sgml (r1.16 -> r1.17)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/contrib.sgml?r1=1.16&r2=1.17)
filelist.sgml (r1.67 -> r1.68)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/filelist.sgml?r1=1.67&r2=1.68)

Added Files:
-----------
pgsql/contrib/pg_upgrade:
Makefile (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/Makefile?rev=1.1&content-type=text/x-cvsweb-markup)
check.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/check.c?rev=1.1&content-type=text/x-cvsweb-markup)
controldata.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/controldata.c?rev=1.1&content-type=text/x-cvsweb-markup)
dump.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/dump.c?rev=1.1&content-type=text/x-cvsweb-markup)
exec.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/exec.c?rev=1.1&content-type=text/x-cvsweb-markup)
file.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/file.c?rev=1.1&content-type=text/x-cvsweb-markup)
function.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/function.c?rev=1.1&content-type=text/x-cvsweb-markup)
info.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/info.c?rev=1.1&content-type=text/x-cvsweb-markup)
option.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/option.c?rev=1.1&content-type=text/x-cvsweb-markup)
page.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/page.c?rev=1.1&content-type=text/x-cvsweb-markup)
pg_upgrade.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/pg_upgrade.c?rev=1.1&content-type=text/x-cvsweb-markup)
pg_upgrade.h (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/pg_upgrade.h?rev=1.1&content-type=text/x-cvsweb-markup)
pg_upgrade_sysoids.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/pg_upgrade_sysoids.c?rev=1.1&content-type=text/x-cvsweb-markup)
relfilenode.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/relfilenode.c?rev=1.1&content-type=text/x-cvsweb-markup)
server.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/server.c?rev=1.1&content-type=text/x-cvsweb-markup)
tablespace.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/tablespace.c?rev=1.1&content-type=text/x-cvsweb-markup)
util.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/util.c?rev=1.1&content-type=text/x-cvsweb-markup)
version.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/version.c?rev=1.1&content-type=text/x-cvsweb-markup)
version_old_8_3.c (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/version_old_8_3.c?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/doc/src/sgml:
pgupgrade.sgml (r1.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/pgupgrade.sgml?rev=1.1&content-type=text/x-cvsweb-markup)