pgsql: When querying a table with child tables, do not check permissions

Log Message:
-----------
When querying a table with child tables, do not check permissions on the
child tables.  This was found to be useless and confusing in virtually all
cases, and also contrary to the SQL standard.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        ddl.sgml (r1.87 -> r1.88)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ddl.sgml?r1=1.87&r2=1.88)
    pgsql/src/backend/optimizer/prep:
        prepunion.c (r1.176 -> r1.177)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/prep/prepunion.c?r1=1.176&r2=1.177)
    pgsql/src/test/regress/expected:
        privileges.out (r1.50 -> r1.51)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/privileges.out?r1=1.50&r2=1.51)
    pgsql/src/test/regress/sql:
        privileges.sql (r1.29 -> r1.30)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/privileges.sql?r1=1.29&r2=1.30)