qt: Use IsMine to validate custom change address

(cherry picked from commit c41224dfd51c896341bbf2fa23e160bf5ffe27c3)

src/qt/sendcoinsdialog.cpp

@@ -789,10 +789,8 @@ void SendCoinsDialog::coinControlChangeEdited(const QString& text)
         }
         else // Valid address
         {
-            CKeyID keyid;
+            const CTxDestination dest = addr.Get();
-            addr.GetKeyID(keyid);
+            if (!model->IsSpendable(dest)) {
-            if (!model->havePrivKey(keyid)) // Unknown change address
-            {
                 ui->labelCoinControlChangeLabel->setText(tr("Warning: Unknown change address"));
 
                 // confirmation dialog
@@ -800,7 +798,7 @@ void SendCoinsDialog::coinControlChangeEdited(const QString& text)
                     QMessageBox::Yes | QMessageBox::Cancel, QMessageBox::Cancel);
 
                 if(btnRetVal == QMessageBox::Yes)
-                    CoinControlDialog::coinControl->destChange = addr.Get();
+                    CoinControlDialog::coinControl->destChange = dest;
                 else
                 {
                     ui->lineEditCoinControlChange->setText("");
@@ -819,7 +817,7 @@ void SendCoinsDialog::coinControlChangeEdited(const QString& text)
                 else
                     ui->labelCoinControlChangeLabel->setText(tr("(no label)"));
 
-                CoinControlDialog::coinControl->destChange = addr.Get();
+                CoinControlDialog::coinControl->destChange = dest;
             }
         }
     }

src/qt/walletmodel.cpp

@@ -561,9 +561,9 @@ bool WalletModel::getPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const
     return wallet->GetPubKey(address, vchPubKeyOut);
 }
 
-bool WalletModel::havePrivKey(const CKeyID &address) const
+bool WalletModel::IsSpendable(const CTxDestination& dest) const
 {
-    return wallet->HaveKey(address);
+    return IsMine(*wallet, dest) & ISMINE_SPENDABLE;
 }
 
 bool WalletModel::getPrivKey(const CKeyID &address, CKey& vchPrivKeyOut) const

src/qt/walletmodel.h

@@ -190,7 +190,7 @@ public:
     UnlockContext requestUnlock();
 
     bool getPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const;
-    bool havePrivKey(const CKeyID &address) const;
+    bool IsSpendable(const CTxDestination& dest) const;
     bool getPrivKey(const CKeyID &address, CKey& vchPrivKeyOut) const;
     void getOutputs(const std::vector<COutPoint>& vOutpoints, std::vector<COutput>& vOutputs);
     bool isSpent(const COutPoint& outpoint) const;