Android: use getprop persist.sys.timezone to get and set the time zone

Untested. Maybe
fixes #1351

dnscrypt-proxy/main.go

@@ -27,6 +27,7 @@ type App struct {
 }
 
 func main() {
+	TimezoneSetup()
 	dlog.Init("dnscrypt-proxy", dlog.SeverityNotice, "DAEMON")
 
 	seed := make([]byte, 8)

dnscrypt-proxy/timezone_android.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"os/exec"
+	"strings"
+	"time"
+)
+
+func TimezoneSetup() error {
+	out, err := exec.Command("/system/bin/getprop", "persist.sys.timezone").Output()
+	if err != nil {
+		return err
+	}
+	z, err := time.LoadLocation(strings.TrimSpace(string(out)))
+	if err != nil {
+		return err
+	}
+	time.Local = z
+	return nil
+}

dnscrypt-proxy/timezone_others.go

@@ -0,0 +1,7 @@
+// +build !android
+
+package main
+
+func TimezoneSetup() error {
+	return nil
+}