event/Call: invoke function directly if the EventLoop is dead

Works around a deadlock bug which happens when waiting for an
EventLoop which isn't running anymore.

src/event/Call.cxx

@@ -81,7 +81,7 @@ private:
 void
 BlockingCall(EventLoop &loop, std::function<void()> &&f)
 {
-	if (loop.IsInside()) {
+	if (loop.IsDead() || loop.IsInside()) {
 		/* we're already inside the loop - we can simply call
 		   the function */
 		f();