Remove unused function qt_mac_toCGImageMask

The last usage was removed in ca14d84
when we modernized window masking.

Pick-to: 6.10 6.9 6.8 6.5
Change-Id: Ie7df930f36faf296f31c01cf2ac260607746966d
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

Author: torarnv

src/gui/painting/qcoregraphics.mm

@@ -60,17 +60,6 @@ CGImageRef qt_mac_toCGImage(const QImage &inImage)
     return inImage.convertToFormat(QImage::Format_ARGB32_Premultiplied).toCGImage();
 }
 
-CGImageRef qt_mac_toCGImageMask(const QImage &image)
-{
-    static const auto deleter = [](void *image, const void *, size_t) { delete static_cast<QImage *>(image); };
-    QCFType<CGDataProviderRef> dataProvider =
-            CGDataProviderCreateWithData(new QImage(image), image.bits(),
-                                                    image.sizeInBytes(), deleter);
-
-    return CGImageMaskCreate(image.width(), image.height(), 8, image.depth(),
-                              image.bytesPerLine(), dataProvider, NULL, false);
-}
-
 void qt_mac_drawCGImage(CGContextRef inContext, const CGRect *inBounds, CGImageRef inImage)
 {
     CGContextSaveGState( inContext );

src/gui/painting/qcoregraphics_p.h

@@ -67,7 +67,6 @@ QT_BEGIN_NAMESPACE
 
 #endif
 Q_GUI_EXPORT CGImageRef qt_mac_toCGImage(const QImage &qImage);
-Q_GUI_EXPORT CGImageRef qt_mac_toCGImageMask(const QImage &qImage);
 Q_GUI_EXPORT QImage qt_mac_toQImage(CGImageRef image);
 
 Q_GUI_EXPORT void qt_mac_drawCGImage(CGContextRef inContext, const CGRect *inBounds, CGImageRef inImage);