defer: Move toyrcu to appendix

This move makes room for related work to be pulled in from this LWN
series: https://lwn.net/Articles/619355/, https://lwn.net/Articles/667593/,
and https://lwn.net/Articles/667720/.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
6 files changed