Fix build on wasm

Author: anacrolix

control_unix.go

@@ -1,4 +1,4 @@
-// +build !windows
+// +build !windows,!wasm
 
 package reuseport
 

control_wasm.go

@@ -0,0 +1,9 @@
+package reuseport
+
+import (
+	"syscall"
+)
+
+func Control(network, address string, c syscall.RawConn) error {
+	return nil
+}