track tasks

[ThinkOpenly]

We need to track the respective per-task times of the mutexes also relative to the lifetimes of the tasks.

For example, we may have a task 4 which uses mutex 6 for a total of 2 ms. The task lifetime may be 10 ms, but the trace duration may be 1000 ms. It is interesting to know that the mutex is used for 20% of the task lifetime.