Merge bitcoin#13536: [qt] coincontrol: Remove unused qt4 workaround

faa2cf6 [qt] coincontrol: Remove unused qt4 workaround (MarcoFalke)

Pull request description:

  This reverts 55eade9 since it is no longer required.

Tree-SHA512: ec523d505b410ab72ce9fdee86dfcfe96011472fb386744bb585169724270426ee65da2b527ae47928d604e1f21f54aa2b4b82f9a9d3fbfea1a6516478d81d11
(cherry picked from commit baf3a3a)

# Conflicts:
#	src/qt/coincontroldialog.cpp

src/qt/coincontroldialog.cpp

@@ -135,10 +135,6 @@ CoinControlDialog::CoinControlDialog(QWidget* parent) :
     // Toggle lock state
     connect(ui->pushButtonToggleLock, SIGNAL(clicked()), this, SLOT(buttonToggleLockClicked()));
 
-    // change coin control first column label due Qt4 bug.
-    // see https://github.com/bitcoin/bitcoin/issues/5716
-    ui->treeWidget->headerItem()->setText(COLUMN_CHECKBOX, QString());
-
     ui->treeWidget->setColumnWidth(COLUMN_CHECKBOX, 84);
     ui->treeWidget->setColumnWidth(COLUMN_AMOUNT, 100);
     ui->treeWidget->setColumnWidth(COLUMN_LABEL, 170);