pgsql: Update documentation to reflect the new ALTER OWNER rules for all

Log Message:
-----------
Update documentation to reflect the new ALTER OWNER rules for all
affected types of objects.

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        alter_aggregate.sgml (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_aggregate.sgml.diff?r1=1.6&r2=1.7)
        alter_conversion.sgml (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_conversion.sgml.diff?r1=1.6&r2=1.7)
        alter_database.sgml (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_database.sgml.diff?r1=1.16&r2=1.17)
        alter_domain.sgml (r1.17 -> r1.18)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_domain.sgml.diff?r1=1.17&r2=1.18)
        alter_function.sgml (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_function.sgml.diff?r1=1.8&r2=1.9)
        alter_opclass.sgml (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_opclass.sgml.diff?r1=1.5&r2=1.6)
        alter_operator.sgml (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_operator.sgml.diff?r1=1.1&r2=1.2)
        alter_schema.sgml (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_schema.sgml.diff?r1=1.7&r2=1.8)
        alter_tablespace.sgml (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_tablespace.sgml.diff?r1=1.1&r2=1.2)
        alter_type.sgml (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_type.sgml.diff?r1=1.2&r2=1.3)