Block launch of xretractor 2nd instance

[michalwidera]

Sometimes xretractor appears few times in process list.
In such case tests going crazy.
If I do not catch that artifact I'm looking for different behaviour but not this issue.
This look's non tivial in case of general purpose.

https://www.appsloveworld.com/cplus/100/120/c-c-how-to-tell-if-a-program-is-already-running

We can solve this in script or in C++
Solutions in C++ in most cases looks like system specific
Need to reconsider what is the best solution.