async-bytecomp-allowed-packages should be a list of symbols.

* async-bytecomp.el (async-bytecomp-allowed-packages): Fix docstring.
(package--compile): Check if async-bytecomp-allowed-packages is
a list of one symbol '(all) and not a symbol 'all.

async-bytecomp.el

@@ -46,8 +46,8 @@
   "Packages in this list will be compiled asynchronously by `package--compile'.
 All the dependencies of these packages will be compiled async too,
 so no need to add dependencies to this list.
-The value of this variable can also be the symbol `all', in this case
-packages are always compiled asynchronously."
+The value of this variable can also be a list with a single element,
+the symbol `all', in this case packages are always compiled asynchronously."
   :group 'async
   :type '(repeat (choice symbol)))
 
@@ -133,7 +133,7 @@ All *.elc files are systematically deleted before proceeding."
 
 (defadvice package--compile (around byte-compile-async activate)
   (let ((cur-package (package-desc-name pkg-desc)))
-    (if (or (eq async-bytecomp-allowed-packages 'all)
+    (if (or (equal async-bytecomp-allowed-packages '(all))
             (memq cur-package (async-bytecomp-get-allowed-pkgs)))
         (progn
           (when (eq cur-package 'async)