Factored locking primitives out to their own implementation-dependend

files.  Part of the porting effort to LispWorks.

src/main/buffer.cl

@@ -29,21 +29,14 @@ server needs.")
 with `release-io-buffer', to enable it to be recycled.  Otherwise it
 will just be GC'ed as usual."
   (or
-   #+(and :CMU :MP)
-   (mp:atomic-pop *io-buffers*)
-   #-(and :CMU :MP)
-   (pop *io-buffers*)
-   
+   (pop-atomically *io-buffers*)
    ;; No ready-made buffer, so we create a new one
    (make-new-buffer)))
 
 (defun release-io-buffer (buffer)
   "Return a buffer allocated by `get-io-buffer' to the buffer pool for
 re-use."
-  #+(and :CMU :MP)
-  (mp:atomic-push buffer *io-buffers*)
-  #-(and :CMU :MP)
-  (push buffer *io-buffers*)
+  (push-atomically buffer *io-buffers*)
   t)
 
 (defmacro with-io-buffer ((var) &body body)