Hard-coded constant "16" instead of "CustomColorCount" in qcolordialog.cpp

The line "nextCust = (nextCust+1) % 16;" in the following code snippet uses "16" instead of "QColorDialogStaticData::CustomColorCount" (which is unfortunately not defined in an accessible header file).

void QColorDialogPrivate::_q_addCustom()
{
    QColorDialogOptions::setCustomColor(nextCust, cs->currentColor());
    if (custom)
        custom->update();
    nextCust = (nextCust+1) % 16;
}