torture: Make kvm.sh "--dryrun sched" summarize number of batches

Knowing the number of batches that kvm.sh will split a run into allows
estimation of the duration of a test, give or take the number of builds.
This commit therefore adds a line of output to "--dryrun sched" that
gives the number of batches that will be run.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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

@@ -536,6 +536,8 @@ then
 	egrep 'Start batch|Starting build\.' $T/script |
 		grep -v ">>" |
 		sed -e 's/:.*$//' -e 's/^echo //'
+	nbatches="`grep 'Start batch' $T/script | grep -v ">>" | wc -l`"
+	echo Total number of batches: $nbatches
 	exit 0
 else
 	# Not a dryrun, so run the script.