[COMMITTERS] pgsql: Improve ALTER POLICY tab completion.

Improve ALTER POLICY tab completion. Complete "ALTER POLICY" with a policy name, as we do for DROP POLICY. And, complete "ALTER POLICY polname ON" with a table name that has such a policy, as we do for DROP POLICY, rather than with any table name at all. Masahiko Sawada Branch -- REL9_5_STAB

[COMMITTERS] pgsql: Improve ALTER POLICY tab completion.

Improve ALTER POLICY tab completion. Complete "ALTER POLICY" with a policy name, as we do for DROP POLICY. And, complete "ALTER POLICY polname ON" with a table name that has such a policy, as we do for DROP POLICY, rather than with any table name at all. Masahiko Sawada Branch -- master Det