Add icon for "About Qt" in menu

Use the built-in icon that is also used in the dialog box itself.

src/qt/bitcoingui.cpp

@@ -257,7 +257,7 @@ void BitcoinGUI::createActions()
     aboutAction = new QAction(QIcon(":/icons/bitcoin"), tr("&About Bitcoin"), this);
     aboutAction->setToolTip(tr("Show information about Bitcoin"));
     aboutAction->setMenuRole(QAction::AboutRole);
-    aboutQtAction = new QAction(tr("About &Qt"), this);
+    aboutQtAction = new QAction(QIcon(":/trolltech/qmessagebox/images/qtlogo-64.png"), tr("About &Qt"), this);
     aboutQtAction->setToolTip(tr("Show information about Qt"));
     aboutQtAction->setMenuRole(QAction::AboutQtRole);
     optionsAction = new QAction(QIcon(":/icons/options"), tr("&Options..."), this);