Running on Android ARM64 fails

[cipriancraciun]

Trying to run a server that uses tcplisten (via fasthttp/reuseport) on Android ARM64 (non jailbroken, Samsung official Android 12) results in the following error:

cannot determine backlog to pass to listen(2): open /proc/sys/net/core/somaxconn: permission denied

I think the issue is that for some reason the Go compiler believes that GOOS=android is a superset of GOOS=linux (when it comes to conditional builds), thus soMaxConn tries to do the auto-detection based on /proc/....

Perhaps a simple change in soMaxConn that checks if it's not actually running on Linux (looking at runtime.GOOS == "linux") would suffice.