WSAPoll and minimum supported windows

[pachuco]

SDL3 supports winXP as minimum windows version. WSAPoll is not available there.

Requesting alternate code path for when WSAPoll is not available.

[pachuco]

Haha oops, looks like the rabbit hole is deeper. #149

This makes windowses below windows 10 v2004 unfit to use WSAPoll as-is.

[icculus]

Yeah, I just read up on this for the XP compatibility issue. :/

It seems like the right thing to do is use select() with a custom struct to avoid the 64-socket limit of FD_SETSIZE (a trick that works on WinSock and nothing else), and use it on everything up to Windows 10 (or maybe never use WSAPoll on Windows).

[pachuco]

https://mailman.videolan.org/pipermail/vlc-commits/2015-May/030508.html
https://github.com/videolan/vlc/blob/master/compat/poll.c
Found this in the meanwhile.

Seems to be working in winxp x86 vmware.
It works on my win7 x86 machine.
And it works on my win10 x86_64 machine.

Bueno.

[pachuco]

I tried using the function as winapi shim, and crashed qTox with it. The hack-up function poll() that gets called before poll_compat() is causing the crash. So, yeeeeeeah...

[icculus]

Okay, this uses select() on Windows now, with some hackery to make it work with arbitrary numbers of sockets at a time.

It works for the echo-server example, but I'd like feedback if you are able to put it to work on a more-serious workload.