Watchdog: conditionally check network

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -876,6 +876,8 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
     private void onWatchdog(Intent intent) {
         EntityLog.log(this, "Watchdog");
         schedule(this, false);
+
+        if (lastNetworkState == null || !lastNetworkState.isSuitable())
             updateNetworkState(null, "watchdog");
     }