rcu: Consolidate rcu_synchronize and wakeme_after_rcu()

There are currently duplicate identical definitions of the
rcu_synchronize() structure and the wakeme_after_rcu() function.
Thie commit therefore consolidates them.

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

diff --cc include/linux/rcupdate.h
Simple merge

diff --cc kernel/rcu/srcu.c
Simple merge

diff --cc kernel/rcu/update.c
Simple merge