rcutorture: Add RCU-tasks test cases

This commit adds the TASKS01 and TASKS02 Kconfig fragments, along with
the corresponding TASKS01.boot and TASKS02.boot boot-parameter files
specifying that rcutorture test RCU-tasks instead of the default flavor.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/configs/rcu/TASKS01

+CONFIG_SMP=y
+CONFIG_NR_CPUS=2
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_DEBUG_LOCK_ALLOC=y
+CONFIG_PROVE_RCU=y
+CONFIG_TASKS_RCU=y

tools/testing/selftests/rcutorture/configs/rcu/TASKS01.boot

+rcutorture.torture_type=tasks

tools/testing/selftests/rcutorture/configs/rcu/TASKS02

+CONFIG_SMP=n
+CONFIG_PREEMPT_NONE=y
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=n
+CONFIG_TASKS_RCU=y

tools/testing/selftests/rcutorture/configs/rcu/TASKS02.boot

+rcutorture.torture_type=tasks

tools/testing/selftests/rcutorture/configs/rcu/TASKS03

+CONFIG_SMP=y
+CONFIG_NR_CPUS=2
+CONFIG_HOTPLUG_CPU=n
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_TASKS_RCU=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=n
+CONFIG_NO_HZ_FULL=y
+CONFIG_NO_HZ_FULL_ALL=y

tools/testing/selftests/rcutorture/configs/rcu/TASKS03.boot

+rcutorture.torture_type=tasks