Don't add markers for unknown ETW events

[vvuk]

These are useful for debugging and might be a nice command line option in the future, but for now they just add random Image/UnLoad and Process/Terminated events which aren't useful

[mstange]

Would you be happy if we just ignored UnLoad and Terminated? I think @jrmuizel likes to experiment with different xperf start settings and then it's convenient to just have the new markers show up immediately.

[vvuk]

Yeah, I was actually thinking of just adding a command line flag to make markers for unknown things, because it is pretty useful. Would that work? Specifically:

• Ignore Image/UnLoad and Process/Terminate
• add a --unknown-event-markers command line flag to enable generating markers for unknown events

? I'd like an option instead of doing it unilaterally so that if I'm importing an etl file created elsewhere, it may contain lots of events that I don't care about at all, but may end up as a large volume of markers.

[vvuk]

Ok, reworked this to add the command line option; let me know if that works.