Add match arm for unused builtin resource managers

Although we don't currently handle these, they are much different from
an unrecognized resource manager, which the comment in the last match
arm refers to.

pgxn/neon/neon.c

@@ -838,7 +838,7 @@ wal_log_file(PG_FUNCTION_ARGS)
  * Entry point for `postgres --wal-log`.
  */
 PGDLLEXPORT void
-WalLogMain(int argc, char *argv[])
+WalLog(int argc, char *argv[])
 {
 	int			rc;
 	int			fd;