Merge #12381: Remove more boost threads

004f999 boost: drop boost threads for [alert|block|wallet]notify (Cory Fields)
0827267 boost: drop boost threads from torcontrol (Cory Fields)
ba91724 boost: remove useless threadGroup parameter from Discover (Cory Fields)
f26866b boost: drop boost threads for upnp (Cory Fields)

Pull request description:

  This doesn't completely get rid of boost::thread, but this batch should be easy to review, and leaves us with only threadGroup (scheduler + scriptcheck) remaining.

  Note to reviewers: The upnp diff changes a bunch of whitespace, it's much more clear with 'git diff -w'

Tree-SHA512: 5a356798d0785f93ed143d1f0afafe890bc82f0d470bc969473da2d2aa78bcb9b096f7ba11b92564d546fb447d4bd0d347e7842994ea0170aafd53fda7e0a66e

src/init.cpp

@@ -165,6 +165,7 @@ void Interrupt()
     InterruptRPC();
     InterruptREST();
     InterruptTorControl();
+    InterruptMapPort();
     if (g_connman)
         g_connman->Interrupt();
 }
@@ -191,7 +192,7 @@ void Shutdown()
 #ifdef ENABLE_WALLET
     FlushWallets();
 #endif
-    MapPort(false);
+    StopMapPort();
 
     // Because these depend on each-other, we make sure that neither can be
     // using the other before destroying them.
@@ -545,7 +546,8 @@ static void BlockNotifyCallback(bool initialSync, const CBlockIndex *pBlockIndex
     std::string strCmd = gArgs.GetArg("-blocknotify", "");
     if (!strCmd.empty()) {
         boost::replace_all(strCmd, "%s", pBlockIndex->GetBlockHash().GetHex());
-        boost::thread t(runCommand, strCmd); // thread runs free
+        std::thread t(runCommand, strCmd);
+        t.detach(); // thread runs free
     }
 }
 
@@ -1674,12 +1676,14 @@ bool AppInitMain()
     LogPrintf("nBestHeight = %d\n", chain_active_height);
 
     if (gArgs.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION))
-        StartTorControl(threadGroup, scheduler);
+        StartTorControl();
 
-    Discover(threadGroup);
+    Discover();
 
     // Map ports with UPnP
-    MapPort(gArgs.GetBoolArg("-upnp", DEFAULT_UPNP));
+    if (gArgs.GetBoolArg("-upnp", DEFAULT_UPNP)) {
+        StartMapPort();
+    }
 
     CConnman::Options connOptions;
     connOptions.nLocalServices = nLocalServices;