Set default values of stty according to the man page

This configuration is basically 38400 8N1, without echo and
in raw mode. Kernel will not process any of the characters
sent by the user.

config.def.h

@@ -18,7 +18,7 @@ static int borderpx = 2;
  */
 static char shell[] = "/bin/sh";
 static char *utmp = NULL;
-static char stty_args[] = "stty raw -echo -iexten echonl";
+static char stty_args[] = "stty raw pass8 nl -echo -iexten -cstopb 38400";
 
 /* identification sequence returned in DA and DECID */
 static char vtiden[] = "\033[?6c";