pgsql: Move pg_upgrade shared library out into its own /contrib

Log Message:
-----------
Move pg_upgrade shared library out into its own /contrib directory
(pg_upgrade_support).

Modified Files:
--------------
    pgsql/contrib:
        Makefile (r1.91 -> r1.92)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile?r1=1.91&r2=1.92)
    pgsql/contrib/pg_upgrade:
        Makefile (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/Makefile?r1=1.2&r2=1.3)
        check.c (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/check.c?r1=1.1&r2=1.2)
        function.c (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/function.c?r1=1.1&r2=1.2)
    pgsql/doc/src/sgml:
        pgupgrade.sgml (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/pgupgrade.sgml?r1=1.1&r2=1.2)

Added Files:
-----------
    pgsql/contrib/pg_upgrade_support:
        Makefile (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade_support/Makefile?rev=1.1&content-type=text/x-cvsweb-markup)
        pg_upgrade_support.c (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade_support/pg_upgrade_support.c?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/contrib/pg_upgrade:
        pg_upgrade_sysoids.c
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_upgrade/pg_upgrade_sysoids.c)