rcu: repair code-duplication FIXMEs

Combine the duplicate definitions of ULONG_CMP_GE(), ULONG_CMP_LT(),
and rcu_preempt_depth() into include/linux/rcupdate.h.

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

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

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

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

diff --cc kernel/rcutiny_plugin.h
Simple merge

diff --cc kernel/rcutree.h
Simple merge