Fix encoding and display of messages sent by server to emacsclient

* lisp/server.el (server-start): Use 'locale-coding-system' to
encode messages sent back to the client.

* lib-src/emacsclient.c (main): Print '-error' messages via
'message', not directly via 'fprintf'.  This shows the error on
MS-Windows when the client is invoked as 'emacsclientw', since
stderr goes to the bit bucket in that case.

lib-src/emacsclient.c

@@ -2240,7 +2240,7 @@ main (int argc, char **argv)
               char *str = unquote_argument (p + strlen ("-error "));
               if (!skiplf)
                 printf ("\n");
-              fprintf (stderr, "*ERROR*: %s", str);
+	      message (true, "*ERROR*: %s", str);
               if (str[0])
 	        skiplf = str[strlen (str) - 1] == '\n';
               exit_status = EXIT_FAILURE;