Avoid warning: Ignoring window icon xxx exceeds maximum xcb request length 65535

Using a svg for window icon when run with X11 and device-pixel-ratio 2 or more produces warning:

Ignoring window icon 93367 exceeds maximum xcb request length 65535 

Warning is produced by QXcbWindow::setWindowIcon() that in this case:

• as icon.availableSizes() is empty it will it accumulate pixels for pixmaps with sizes [16, 32, 64, 128]
• if total size of accumulated pixel data exceeds the xcb maximum request size it will produce the warning and no icon will be set

With device-pixel-ratio of 2 just for the size of 128 the required amount of pixels is: (128*2)^2 = 65536 which matches xcb max request size.

I would prefer if this warning is avoided as we run our project in a mode where Qt warnings are considered fatal.

Following program can be used to reproduce the problem as long as it is run on linux and device-pixel-ratio is 2 or larger.

#include <QApplication>
#include <QWindow>
#include <QScreen>
#include <iostream>

void qt_log_handler(QtMsgType , const QMessageLogContext &, const QString &msg) {
    std::cerr << msg.toStdString() << "\n";
}

int main(int argc, char *argv[]) {    
    QApplication app(argc, argv);

    QScreen *screen = QGuiApplication::primaryScreen();
    std::cerr << "devicePixelRatio: " << screen->devicePixelRatio() << "\n";

    qInstallMessageHandler(qt_log_handler);
    QWindow window;    
    window.setIcon(QIcon(QLatin1String("some.svg")));
    window.show();

    return app.exec();
} 

Size/dpi info for display:

$ DISPLAY=:2 xrandr
Screen 0: minimum 32 x 32, current 3456 x 1932, maximum 16384 x 16384
VNC-0 connected 3456x1932+0+0 442mm x 246mm
   3456x1932     60.00*+ 

I'd suggest as a fix: when image_data is accumulated sizes loop skips sizes that would exceed xcb max request size. If none of the sizes was used a warning is produced.