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.

config/kernel.m4

@@ -29,6 +29,8 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_RQ_IS_SYNC
 	ZFS_AC_KERNEL_RQ_FOR_EACH_SEGMENT
 	ZFS_AC_KERNEL_CONST_XATTR_HANDLER
+	ZFS_AC_KERNEL_XATTR_HANDLER_GET
+	ZFS_AC_KERNEL_XATTR_HANDLER_SET
 	ZFS_AC_KERNEL_FSYNC_2ARGS
 
 	if test "$LINUX_OBJ" != "$LINUX"; then