torture: Create KCSAN summaries for torture.sh runs

Currently, each -kcsan run in a torture.sh group of runs has its own
kcsan.sum summary.  This works, but there is usually a lot of duplication
between the runs.  This commit therefore also creates an overall kcsan.sum
file for the entire torture.sh run, if there was at least one -kcsan run.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/torture.sh

@@ -418,6 +418,10 @@ then
 	nfailures="`wc -l "$T/failures" | awk '{ print $1 }'`"
 	ret=2
 fi
+if test "$do_kcsan" = "yes"
+then
+	TORTURE_KCONFIG_KCSAN_ARG=1 tools/testing/selftests/rcutorture/bin/kcsan-collapse.sh tools/testing/selftests/rcutorture/res/$ds > tools/testing/selftests/rcutorture/res/$ds/kcsan.sum
+fi
 echo Started at $startdate, ended at `date`, duration `get_starttime_duration $starttime`. | tee -a $T/log
 echo Summary: Successes: $nsuccesses Failures: $nfailures. | tee -a $T/log
 tdir="`cat $T/successes $T/failures | head -1 | awk '{ print $NF }' | sed -e 's,/[^/]\+/*$,,'`"