Interrupt loading thread after shutdown request

Github-Pull: #12415
Rebased-From: 2e9406c0c588ddf6f039fd3ff73c978177483869
Tree-SHA512: ad70df9fdcba38bc9eeac4e4e64f7d8607fbe92aefac3579a26939e642112d70ebee81c5a227bb8735bae87f95640061a5ab22b583275c7dd6c3277544bc427b

src/init.cpp

@@ -678,11 +678,13 @@ void ThreadImport(std::vector<fs::path> vImportFiles)
     if (!ActivateBestChain(state, chainparams)) {
         LogPrintf("Failed to connect best block");
         StartShutdown();
+        return;
     }
 
     if (gArgs.GetBoolArg("-stopafterblockimport", DEFAULT_STOPAFTERBLOCKIMPORT)) {
         LogPrintf("Stopping after block import\n");
         StartShutdown();
+        return;
     }
     } // End scope of CImportingNow
     if (gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {