driver/*.c: Add response for get_arg("mmc-supported?")

example/*.c: remove compiler wranings.

lib/driver/netbsd.c

@@ -1,7 +1,5 @@
 /*
-  $Id: netbsd.c,v 1.4 2008/04/22 15:29:12 karl Exp $
- 
-  Copyright (C) 2008 Rocky Bernstein <rocky@gnu.org>
+  Copyright (C) 2008, 2010 Rocky Bernstein <rocky@gnu.org>
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -372,6 +370,8 @@ get_arg_netbsd(void *user_data, const char key[])
 		return _obj->gen.source_name;
 	} else if (!strcmp(key, "access-mode")) {
 		return "READ_CD";
+        } else if (!strcmp (key, "mmc-supported?")) {
+            return "true" ;
 	}
 
 	return NULL;