http: Remove unnecessary event_base_loopexit call

Let event base loop exit cleanly by processing all active and pending
events. The call is no longer necessary because closing persistent
connections is now properly handled.

src/httpserver.cpp

@@ -470,8 +470,6 @@ void StopHTTPServer()
     boundSockets.clear();
     if (eventBase) {
         LogPrint(BCLog::HTTP, "Waiting for HTTP event thread to exit\n");
-        // Exit the event loop as soon as there are no active events.
-        event_base_loopexit(eventBase, nullptr);
         // Give event loop a few seconds to exit (to send back last RPC responses), then break it
         // Before this was solved with event_base_loopexit, but that didn't work as expected in
         // at least libevent 2.0.21 and always introduced a delay. In libevent