Binary break in Qt 5.10 pre-alpha

There is an ABI break in Qt 5.10 pre-alpha. It's caused by this commit: 4de40514066e7e31fe02c87afaf0863d6928391f

Here's a fix for it: https://codereview.qt-project.org/#/c/202511/

However, the ultimate question is why it wasn't caught in the BIC tests...