Work around go fd closing limitation and version bump

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/build.gradle

@@ -20,7 +20,7 @@ android {
         applicationId 'com.wireguard.android'
         minSdkVersion 21
         targetSdkVersion 27
-        versionCode 402
+        versionCode 403
         versionName '0.4.0'
     }
     externalNativeBuild {

app/tools/libwg-go/api-android.go

@@ -11,6 +11,7 @@ import (
 	"math"
 	"os"
 	"strings"
+	"syscall"
 )
 
 type AndroidLogger struct {
@@ -42,11 +43,23 @@ func wgTurnOn(ifnameRef string, tun_fd int32, settings string) int32 {
 	logger.Debug.Println("Debug log enabled")
 
 	tun := &NativeTun{
-		fd:     os.NewFile(uintptr(tun_fd), ""),
+		fd:     os.NewFile(uintptr(tun_fd), "/dev/tun"),
 		events: make(chan TUNEvent, 5),
 		errors: make(chan error, 5),
 		nopi:   true,
 	}
+	var err error
+
+	err = syscall.SetNonblock(int(tun_fd), true)
+	if err != nil {
+		logger.Error.Println(err)
+		return -1
+	}
+	tun.closingReader, tun.closingWriter, err = os.Pipe()
+	if err != nil {
+		logger.Error.Println(err)
+		return -1
+	}
 	name, err := tun.Name()
 	if err != nil {
 		logger.Error.Println(err)

app/tools/wireguard-go

@@ -1 +1 @@
-Subproject commit ac9912345b4da5034ea93f5f245ea2ce04815bd5
+Subproject commit ec28113c7eebd93c87964a3509460fd150ad5ac7