Row security policies disregard user ID changes after inlining.

PostgreSQL could permit incorrect policies to be applied in certain cases where role-specific policies are used and a given query is planned under one role and then executed under other roles. This scenario can happen under security definer functions or when a common user and query is planned initially and then re-used across multiple SET ROLEs. Applying an incorrect policy may permit a user to complete otherwise-forbidden reads and modifications. This affects only databases that have used CREATE POLICY to define a row security policy.