QThread::setPriority fails with SCHED_RESET_ON_FORK

In case of Pipewire the scheduler policy is "SCHED_RESET_ON_FORK | SCHED_FIFO"

In this case QThread::setPriority() fails with

"QThread::setPriority: Cannot determine scheduler priority range"

this is because the sub-call "sched_get_priority_max()" returns -1 with SCHED_RESET_ON_FORK set.

Without the flag everything works flawlessly.

This has been tested on Ubuntu Focal and Qt 5.12.8 but the code is still the same in the "dev" branch so I assume that more recent versions are also affected.

https://github.com/qt/qtbase/blob/7191b8fe38788ac57e15e4124955c3cd8333d858/src/corelib/thread/qthread_unix.cpp#L819