macOS: Ignore deprecation for ReleaseIconRef

There's no good replacement yet for our use of GetIconRef
and ReleaseIconRef, so for now ignore the deprecation.

Pick-to: 6.2 6.3 6.4 5.15
Change-Id: Iffcaa2af3c9e2ee053303a2272e8874913dd74d4
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

src/plugins/platforms/cocoa/qcocoatheme.mm

@@ -379,7 +379,7 @@ QPixmap QCocoaTheme::standardPixmap(StandardPixmap sp, const QSizeF &size) const
 
         if (icon) {
             pixmap = qt_mac_convert_iconref(icon, size.width(), size.height());
-            ReleaseIconRef(icon);
+            QT_IGNORE_DEPRECATIONS(ReleaseIconRef(icon));
         }
 
         return pixmap;