Don't use zero as null pointer constant (-Wzero-as-null-pointer-constant)

Qt-only changes.

src/qt/sendcoinsdialog.cpp

@@ -54,8 +54,8 @@ int getIndexForConfTarget(int target) {
 SendCoinsDialog::SendCoinsDialog(const PlatformStyle *_platformStyle, QWidget *parent) :
     QDialog(parent),
     ui(new Ui::SendCoinsDialog),
-    clientModel(0),
-    model(0),
+    clientModel(nullptr),
+    model(nullptr),
     fNewRecipientAllowed(true),
     fFeeMinimized(true),
     platformStyle(_platformStyle)
@@ -443,7 +443,7 @@ SendCoinsEntry *SendCoinsDialog::addEntry()
 
 void SendCoinsDialog::updateTabsAndLabels()
 {
-    setupTabChain(0);
+    setupTabChain(nullptr);
     coinControlUpdateLabels();
 }
 
@@ -478,7 +478,7 @@ QWidget *SendCoinsDialog::setupTabChain(QWidget *prev)
 
 void SendCoinsDialog::setAddress(const QString &address)
 {
-    SendCoinsEntry *entry = 0;
+    SendCoinsEntry *entry = nullptr;
     // Replace the first entry if it is still unused
     if(ui->entries->count() == 1)
     {
@@ -501,7 +501,7 @@ void SendCoinsDialog::pasteEntry(const SendCoinsRecipient &rv)
     if(!fNewRecipientAllowed)
         return;
 
-    SendCoinsEntry *entry = 0;
+    SendCoinsEntry *entry = nullptr;
     // Replace the first entry if it is still unused
     if(ui->entries->count() == 1)
     {