Break out multicast into a separate package

src/multicast/multicast_other.go

@@ -0,0 +1,13 @@
+// +build !linux,!darwin,!netbsd,!freebsd,!openbsd,!dragonflybsd,!windows
+
+package multicast
+
+import "syscall"
+
+func (m *Multicast) multicastStarted() {
+
+}
+
+func (m *Multicast) multicastReuse(network string, address string, c syscall.RawConn) error {
+	return nil
+}