Reduce logging

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

@@ -4156,6 +4156,7 @@ class Core {
                     // https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.State.html
                     Thread.State state = thread.getState();
                     if (thread.isAlive()) {
+                        if (interrupted)
                             Log.e("Join " + name + " failed state=" + state + " interrupted=" + interrupted);
                         if (interrupted)
                             joined = true; // give up