The syscall interface is has been replaced by a more flexible
interface since 2.6.0.  It is time to work towards discarding
the old interface.

So add a entry in feature-removal-schedule.txt and print a warning
when the interface is used.
Signed-off-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>