torture: Place --bootargs parameters at end of -append list

Currently, the kernel boot parameters specified by the kvm.sh --bootargs
parameter are placed near the beginning of the -append list that is
passed to qemu. This means that in the not-uncommon case of a kernel
boot parameter where the last argument wins, the --bootargs list overrides
neither the list in the .boot file nor the additional parameters supplied
by the rcutorture scripting.

This commit therefore places the kernel boot parameters specified by
the kvm.sh --bootargs parameter at the end of qemu's -append list.

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

tools/.../rcutorture: Convert to SPDX license identifier

Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address and add copyright notices.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

torture: Eliminate torture_runnable and perf_runnable

The purpose of torture_runnable is to allow rcutorture and locktorture
to be started and stopped via sysfs when they are built into the kernel
(as in not compiled as loadable modules). However, the 0444 permissions
for both instances of torture_runnable prevent this use case from ever
being put into practice. Given that there have been no complaints
about this deficiency, it is reasonable to conclude that no one actually
makes use of this sysfs capability. The perf_runnable module parameter
for rcuperf is in the same situation.

This commit therefore removes both torture_runnable instances as well
as perf_runnable.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

locktorture: Make torture scripting account for new _runnable name

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

locktorture: Add vestigial locktorture configuration

This commit adds a trivial set of configuration files for lock
torturing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>