Allow a nullptr callback for event loop PumpLL

llarp/ev/ev_libuv.cpp

@@ -111,13 +111,14 @@ namespace llarp::uv
   {
     llarp::LogTrace("ticking event loop.");
     FlushLogic();
-    PumpLL();
+    if (PumpLL)
+      PumpLL();
     auto& log = llarp::LogContext::Instance();
     if (log.logStream)
       log.logStream->Tick(time_now());
   }
 
-  Loop::Loop(size_t queue_size) : llarp::EventLoop{}, PumpLL{[] {}}, m_LogicCalls{queue_size}
+  Loop::Loop(size_t queue_size) : llarp::EventLoop{}, PumpLL{nullptr}, m_LogicCalls{queue_size}
   {
     if (!(m_Impl = uvw::Loop::create()))
       throw std::runtime_error{"Failed to construct libuv loop"};