wgengine/magicsock: disable SIO_UDP_NETRESET on Windows

By default, Windows sets the SIO_UDP_CONNRESET and SIO_UDP_NETRESET
options on created UDP sockets. These behaviours make the UDP socket
ICMP-aware; when the system gets an ICMP message (e.g. an "ICMP Port
Unreachable" message, in the case of SIO_UDP_CONNRESET), it will cause
the underlying UDP socket to throw an error. Confusingly, this can occur
even on reads, if the same UDP socket is used to write a packet that
triggers this response.

The Go runtime disabled the SIO_UDP_CONNRESET behavior in 3114bd6, but
did not change SIO_UDP_NETRESET–probably because that socket option
isn't documented particularly well.

Various other networking code seem to disable this behaviour, such as
the Godot game engine (godotengine/godot#22332) and the Eclipse TCF
agent (link below). Others appear to work around this by ignoring the
error returned (anacrolix/dht#16, among others).

For now, until it's clear whether this ends up in the upstream Go
implementation or not, let's also disable the SIO_UDP_NETRESET in a
similar manner to SIO_UDP_CONNRESET.

Eclipse TCF agent: https://gitlab.eclipse.org/eclipse/tcf/tcf.agent/-/blob/master/agent/tcf/framework/mdep.c

Updates #10976
Updates golang/go#68614

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I70a2f19855f8dec1bfb82e63f6d14fc4a22ed5c3

wgengine/magicsock/magicsock.go

@@ -2538,6 +2538,7 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
 			}
 		}
 		trySetSocketBuffer(pconn, c.logf)
+		trySetUDPSocketOptions(pconn, c.logf)
 
 		// Success.
 		if debugBindSocket() {