rcu: Make rcu_read_unlock_special() expedite strict grace periods

In kernels built with CONFIG_RCU_STRICT_GRACE_PERIOD=y, every grace
period is an expedited grace period.  However, rcu_read_unlock_special()
does not treat them that way, instead allowing the deferred quiescent
state to be reported whenever.  This commit therefore adds a check of
this Kconfig option that causes rcu_read_unlock_special() to treat all
grace periods as expedited for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>