torture: Make kvm.sh summaries note runs having only KCSAN reports

Runs having only KCSAN reports will normally print a summary line
containing only a "Bugs:" entry.  However, these bugs might or might
not be KCSAN reports.  This commit therefore flags runs in which all the
"Bugs:" entries are KCSAN reports.

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