Allow new values to be added to an existing enum type.

After much expenditure of effort, we've got this to the point where the
performance penalty is pretty minimal in typical cases.

Andrew Dunstan, reviewed by Brendan Jurd, Dean Rasheed, and Tom Lane

contrib/pg_upgrade/function.c

@@ -79,7 +79,7 @@ install_support_functions(void)
 								  "LANGUAGE C STRICT;"));
 		PQclear(executeQueryOrDie(conn,
 								  "CREATE OR REPLACE FUNCTION "
-			 "		binary_upgrade.add_pg_enum_label(OID, OID, NAME) "
+			 "		binary_upgrade.set_next_pg_enum_oid(OID) "
 								  "RETURNS VOID "
 								  "AS '$libdir/pg_upgrade_support' "
 								  "LANGUAGE C STRICT;"));