lib/osutil: Disable setting priority on Windows (fixes #4676)

[calmh]

Presumably fixing the crash, leaving us to improve this calmly.

[calmh]

@st-review merge

[st-review]

👌 Merged as 582539a. Thanks, @calmh!

[AudriusButkevicius]

I guess this is so urgent as you want a new RC?

[calmh]

Yeah printing one currently

[calmh]

Can try to get a fixed version into an rc3, but lets not crash in the meantime

[AudriusButkevicius]

I hopefully can test this, yet not until friday I suspect.

[calmh]

I can see a couple of things that might go wrong. I'm blindly assuming that kernel32.dll is available (and we do that in other places) and that SetPriorityClass is found. That may not be the case. The process handle in the crash backtrace is 0xffffffff which is suspicious (but maybe valid, I don't know, could mean "self"), yet that is one call where we do check the error. And of course I might have misunderstood something else.

[AudriusButkevicius]

I suspect it crashes due to an exception/fault/whatever it's called raised during the syscall, and the exception is raised because something is not found or not valid.