rcu: Directly drive TASKS_RCU from Kconfig

rcu: Directly drive TASKS_RCU from Kconfig

Currently, Kconfig will ask the user whether TASKS_RCU should be set.
This is silly because Kconfig already has all the information that it
needs to set this parameter.  This commit therefore directly drives
the value of TASKS_RCU via "select" statements.  Which means that
as subsystems require TASKS_RCU, those subsystems will need to add
"select" statements of their own.

Reported-by: Ingo Molnar <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Steven Rostedt <[email protected]>
Reviewed-by: Pranith Kumar <[email protected]>