Add some missing schema qualifications

This does not improve the security and reliability of the touched areas,
but it makes the style more consistent.

Author: Michael Paquier
Reviewed-by- Noah Misch
Discussion: https://postgr.es/m/20180309075538.GD9376@paquier.xyz

src/backend/catalog/information_schema.sql

@@ -186,7 +186,7 @@ CREATE FUNCTION _pg_interval_type(typid oid, mod int4) RETURNS text
     AS
 $$SELECT
   CASE WHEN $1 IN (1186) /* interval */
-           THEN upper(substring(format_type($1, $2) from 'interval[()0-9]* #"%#"' for '#'))
+           THEN pg_catalog.upper(substring(pg_catalog.format_type($1, $2) from 'interval[()0-9]* #"%#"' for '#'))
        ELSE null
   END$$;
 

src/bin/psql/command.c

@@ -4578,7 +4578,7 @@ get_create_object_cmd(EditableObjectType obj_type, Oid oid,
 				printfPQExpBuffer(query,
 								  "SELECT nspname, relname, relkind, "
 								  "pg_catalog.pg_get_viewdef(c.oid, true), "
-								  "array_remove(array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, "
+								  "pg_catalog.array_remove(pg_catalog.array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, "
 								  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 								  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption "
 								  "FROM pg_catalog.pg_class c "

src/test/isolation/isolationtester.c

@@ -201,7 +201,7 @@ main(int argc, char **argv)
 		PQclear(res);
 
 		/* Get the backend pid for lock wait checking. */
-		res = PQexec(conns[i], "SELECT pg_backend_pid()");
+		res = PQexec(conns[i], "SELECT pg_catalog.pg_backend_pid()");
 		if (PQresultStatus(res) == PGRES_TUPLES_OK)
 		{
 			if (PQntuples(res) == 1 && PQnfields(res) == 1)