Linux 2.6.33 compat, get/set xattr callbacks

The xattr handler prototypes were sanitized with the idea being that
the same handlers could be used for multiple methods.  The result of
this was the inode type was changes to a dentry, and both the get()
and set() hooks had a handler_flags argument added.  The list()
callback was similiarly effected but no autoconf check was added
because we do not use the list() callback.