pgsql: Add hstore contrib module.

Log Message:
-----------
Add hstore contrib module.
Per discussion
http://archives.postgresql.org/pgsql-hackers/2006-08/msg01409.php

Modified Files:
--------------
pgsql/contrib:
Makefile (r1.68 -> r1.69)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile.diff?r1=1.68&r2=1.69)
README (r1.89 -> r1.90)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/README.diff?r1=1.89&r2=1.90)

Added Files:
-----------
pgsql/contrib/hstore:
Makefile (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/Makefile?rev=1.1&content-type=text/x-cvsweb-markup)
README.hstore (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/README.hstore?rev=1.1&content-type=text/x-cvsweb-markup)
crc32.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/crc32.c?rev=1.1&content-type=text/x-cvsweb-markup)
crc32.h (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/crc32.h?rev=1.1&content-type=text/x-cvsweb-markup)
hstore.h (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/hstore.h?rev=1.1&content-type=text/x-cvsweb-markup)
hstore.sql.in (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/hstore.sql.in?rev=1.1&content-type=text/x-cvsweb-markup)
hstore_gist.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/hstore_gist.c?rev=1.1&content-type=text/x-cvsweb-markup)
hstore_io.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/hstore_io.c?rev=1.1&content-type=text/x-cvsweb-markup)
hstore_op.c (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/hstore_op.c?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/contrib/hstore/data:
hstore.data (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/data/hstore.data?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/contrib/hstore/expected:
hstore.out (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/expected/hstore.out?rev=1.1&content-type=text/x-cvsweb-markup)
pgsql/contrib/hstore/sql:
hstore.sql (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/sql/hstore.sql?rev=1.1&content-type=text/x-cvsweb-markup)