rcutorture: Provide rudimentary Makefile

This commit provides a rudimentary Makefile that runs a 10-minute
rcutorture test on scenario TREE01. This must be run on a system capable
of spawning virtual machines and with everything installed to permit
building Linux kernels.

Reported-by: Shuah Khan <[e-mail]>
Signed-off-by: Paul E. McKenney <[e-mail]>

tools/testing/selftests/rcutorture/Makefile

···
+# SPDX-License-Identifier: GPL-2.0+
+all:
+	( cd ../../../..; tools/testing/selftests/rcutorture/bin/kvm.sh --duration 10 --configs TREE01 )