Fix syntax error when schema in not in search_path

When schema, which must be masked, is not in the search_path, will be syntax error:

=> create schema m; CREATE SCHEMA => create table m.a(a int); CREATE TABLE => select anon.start_dynamic_masking('m'); ERROR: cross-database references are not implemented: "mask.m.a" CONTEXT: SQL statement "CREATE OR REPLACE VIEW "mask".m.a AS SELECT a FROM m.a" PL/pgSQL function anon.mask_create_view(oid) line 3 at EXECUTE SQL function "mask_update" statement 2 SQL statement "SELECT anon.mask_update()" PL/pgSQL function anon.start_dynamic_masking(text,text,boolean) line 27 at PERFORM

This commit fix this.