Fix Windows shutdown hang and register console ctrl handler

- Remove GenerateBitcoins(false) from stop RPC handler because it calls
  minerThreads->join_all() which blocks the RPC thread, preventing the
  response from being sent back to the client. Miners are already stopped
  in Shutdown() so this was redundant.
- Add ShutdownRequested() checks in miner peer-wait and nonce loops
- Register SetConsoleCtrlHandler on Windows for clean Ctrl+C/close
- Add check_and_clean_target for --linux-release builds

src/miner.cpp

@@ -34,6 +34,7 @@
 #include "RandomX/src/randomx.h"
 #endif
 #include "hash.h"
+#include "init.h"
 #include "key_io.h"
 #include "main.h"
 #include "metrics.h"
@@ -1302,6 +1303,8 @@ void static RandomXMiner()
                     }
                     if (!fvNodesEmpty )//&& !IsInitialBlockDownload())
                         break;
+                    if (ShutdownRequested())
+                        throw boost::thread_interrupted();
                     MilliSleep(15000);
                     //fprintf(stderr,"fvNodesEmpty %d IsInitialBlockDownload(%s) %d\n",(int32_t)fvNodesEmpty,SMART_CHAIN_SYMBOL,(int32_t)IsInitialBlockDownload());
 
@@ -1570,6 +1573,8 @@ void static RandomXMiner()
                     }
 
                     boost::this_thread::interruption_point();
+                    if (ShutdownRequested())
+                        throw boost::thread_interrupted();
 
                     if (vNodes.empty() && chainparams.MiningRequiresPeers())
                     {
@@ -1702,6 +1707,8 @@ void static BitcoinMiner()
                     }
                     if (!fvNodesEmpty )//&& !IsInitialBlockDownload())
                         break;
+                    if (ShutdownRequested())
+                        throw boost::thread_interrupted();
                     MilliSleep(15000);
                     //fprintf(stderr,"fvNodesEmpty %d IsInitialBlockDownload(%s) %d\n",(int32_t)fvNodesEmpty,SMART_CHAIN_SYMBOL,(int32_t)IsInitialBlockDownload());