(describe-variable): Use local-variable-p.

lisp/help.el

@@ -504,15 +504,8 @@ Returns the documentation as a string, also."
         (princ "void.")
       (prin1 (symbol-value variable)))
     (terpri)
-    (let ((locals (buffer-local-variables))
-	  is-local)
-      (while locals
-	(if (or (eq variable (car locals))
-		(eq variable (car-safe (car locals))))
-	    (setq is-local t locals nil))
-	(setq locals (cdr locals)))
-      (if is-local
-	  (princ (format "Local in buffer %s\n" (buffer-name)))))
+    (if (local-variable-p variable)
+	(princ (format "Local in buffer %s\n" (buffer-name))))
     (terpri)
     (princ "Documentation:")
     (terpri)