Give CMainSignals a reference to the global scheduler

...so that it can run some signals in the background later

src/init.cpp

@@ -251,6 +251,7 @@ void Shutdown()
     }
 #endif
     UnregisterAllValidationInterfaces();
+    GetMainSignals().UnregisterBackgroundSignalScheduler();
 #ifdef ENABLE_WALLET
     for (CWalletRef pwallet : vpwallets) {
         delete pwallet;
@@ -1203,6 +1204,8 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     CScheduler::Function serviceLoop = boost::bind(&CScheduler::serviceQueue, &scheduler);
     threadGroup.create_thread(boost::bind(&TraceThread<CScheduler::Function>, "scheduler", serviceLoop));
 
+    GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
+
     /* Start the RPC server already.  It will be started in "warmup" mode
      * and not really process calls already (but it will signify connections
      * that the server is there and will be ready later).  Warmup mode will