Should disable concurrent extraction only on touch, not for Arm in general

[Michi Henning]

Currently, we are setting max-extractions to 1 on Arm, even when not running on the phone. This means that, on a Chromebook, for example, where we use software codecs, we are not using three idle CPUs. It would be nice to do this only on when running on touch, instead of for both touch and desktop on Arm.

Fixing this involves working out whether we are running on touch, for which no API currently exists. But there is one in the works:

https://codereview.qt-project.org/#/c/101049

[Michi Henning (michihenning)]

Hmmm... That API isn't really what we are after because all it does is tell us what the source of an input event was, such as mouse click or touch-screen press. But we need to know in general.

[Michi Henning (michihenning)]

Tried with 4 concurrent vs-thumb processes on my Chromebook. Turns out that there, I see 4 vs-thumb processes during the stress test, but they all hang (without consuming CPU) after a split second. Eventually, we time out and get a bunch of errors.

Marking this as "won't fix" for the time being. If the gstreamer codecs won't work concurrently, there is nothing we can do.