fix port functions to use byte-ready? instead of char-ready?

svn: r5640

collects/mzlib/port.ss

@@ -159,7 +159,7 @@
 	 try-again
 	 s))
       (define (do-read-it s)
-	(if (char-ready? peeked-r)
+	(if (byte-ready? peeked-r)
             (read-bytes-avail!* s peeked-r)
 	    ;; If nothing is saved from a peeking read,
 	    ;; dispatch to `read', otherwise return
@@ -417,7 +417,7 @@
 				(peek-it s skip #f))])
 	     (lambda (s skip unless-evt)
 	       (if (or unless-evt
-		       (char-ready? peeked-r)
+		       (byte-ready? peeked-r)
 		       (pair? special-peeked))
 		   (peek-it s skip unless-evt)
 		   (fast-peek s skip fast-peek-k))))