refactor: move bdb (bitdb) interaction from init.cpp to wallet.cpp

>>> based on bitcoin/bitcoin@2bb1c87

this will remove db.h from init.cpp

Author: random-zebra

src/init.cpp

@@ -1,10 +1,10 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2015 The Bitcoin developers
+// Copyright (c) 2009-2021 The Bitcoin developers
 // Copyright (c) 2014-2015 The Dash developers
 // Copyright (c) 2011-2013 The PPCoin developers
 // Copyright (c) 2013-2014 The NovaCoin Developers
 // Copyright (c) 2014-2018 The BlackCoin Developers
-// Copyright (c) 2015-2020 The PIVX developers
+// Copyright (c) 2015-2021 The PIVX developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -58,7 +58,6 @@
 #include "zpivchain.h"
 
 #ifdef ENABLE_WALLET
-#include "wallet/db.h"
 #include "wallet/wallet.h"
 #include "wallet/rpcwallet.h"
 
@@ -223,7 +222,7 @@ void PrepareShutdown()
     StopHTTPServer();
 #ifdef ENABLE_WALLET
     if (pwalletMain)
-        bitdb.Flush(false);
+        pwalletMain->Flush(false);
     GenerateBitcoins(false, NULL, 0);
 #endif
     StopMapPort();
@@ -303,7 +302,7 @@ void PrepareShutdown()
     }
 #ifdef ENABLE_WALLET
     if (pwalletMain)
-        bitdb.Flush(true);
+        pwalletMain->Flush(true);
 #endif
 
     if (pEvoNotificationInterface) {

src/wallet/wallet.cpp

@@ -2069,6 +2069,11 @@ std::set<uint256> CWalletTx::GetConflicts() const
     return result;
 }
 
+void CWallet::Flush(bool shutdown)
+{
+    bitdb.Flush(shutdown);
+}
+
 bool CWallet::Verify()
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {

src/wallet/wallet.h

@@ -1128,6 +1128,9 @@ class CWallet : public CCryptoKeyStore, public CValidationInterface
     //! Get wallet transactions that conflict with given transaction (spend same outputs)
     std::set<uint256> GetConflicts(const uint256& txid) const;
 
+    //! Flush wallet (bitdb flush)
+    void Flush(bool shutdown=false);
+
     //! Verify the wallet database and perform salvage if required
     static bool Verify();