torture: Print PID in hung-kernel diagnostic message

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>

tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh

@@ -215,7 +215,7 @@ then
 		fi
 		if test $kruntime -ge $((seconds + grace))
 		then
-			echo "!!! Hang at $kruntime vs. $seconds seconds" >> $resdir/Warnings 2>&1
+			echo "!!! PID $qemu_pid hung at $kruntime vs. $seconds seconds" >> $resdir/Warnings 2>&1
 			kill -KILL $qemu_pid
 			break
 		fi