(ad-compile-function): Fix last change.

lisp/emacs-lisp/advice.el

@@ -2687,7 +2687,7 @@ For that it has to be fbound with a non-autoload definition."
        (let ((symbol (make-symbol "advice-compilation"))
 	     (byte-compile-warnings byte-compile-warnings)
              ;; Don't pop up windows showing byte-compiler warnings.
-             (warning-suppress-types '(bytecomp)))
+             (warning-suppress-types '((bytecomp))))
 	 (if (featurep 'cl)
 	     (byte-compile-disable-warning 'cl-functions))
 	 (fset symbol (symbol-function function))