rcu: Make TASKS_RUDE_RCU select IRQ_WORK

The TASKS_RUDE_RCU does not select IRQ_WORK, which can result in build
failures for kernels that do not otherwise select IRQ_WORK.  This commit
therefore causes the TASKS_RUDE_RCU Kconfig option to select IRQ_WORK.
Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/Kconfig

@@ -86,6 +86,7 @@ config TASKS_RCU
 
 config TASKS_RUDE_RCU
 	def_bool 0
+	select IRQ_WORK
 	help
 	  This option enables a task-based RCU implementation that uses
 	  only context switch (including preemption) and user-mode