rcutorture: Place kvm-test-1-run.sh output into res directory

The output of each kvm-test-1-run.sh script is placed into a file
whose name parallels that of the build directory.  This means that
the kvm-test-1-run.sh output is overwritten by later run.  This
commit therefore places the kvm-test-1-run.sh output into the
per-test-case directory in the "res" hierarchy.

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