Drop "protected"-define from bsd-compatibility header

* drop "protected" from bsd-compat header sys/cdefs.h, as that define
  pollutes the global namespace and at least FreeBSD doesn't provide
  it anymore
* remove all uses of that macro from libedit, which seems to be the
  only user in our tree

headers/compatibility/bsd/sys/cdefs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2010 Haiku Inc. All Rights Reserved.
+ * Copyright 2006-2012 Haiku Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _BSD_SYS_CDEFS_H_
@@ -12,10 +12,6 @@
 #define __FBSDID(x)
 #define __unused
 
-#ifndef __cplusplus
-#	define protected
-#endif
-
 #define __printflike(a, b)	__attribute__ ((format (__printf__, (a), (b))))
 #define __printf0like(a, b)