rename files dealing with low level conns to sys_conn

sys_conn_no_oob.go

@@ -0,0 +1,16 @@
+//go:build !darwin && !linux && !freebsd && !windows
+// +build !darwin,!linux,!freebsd,!windows
+
+package quic
+
+import "net"
+
+func newConn(c net.PacketConn) (connection, error) {
+	return &basicConn{PacketConn: c}, nil
+}
+
+func inspectReadBuffer(interface{}) (int, error) {
+	return 0, nil
+}
+
+func (i *packetInfo) OOB() []byte { return nil }