Merge #12946: depends: Fix Qt build with XCode 9.3
5b4fc3e depends: Fix Qt build with XCode 9.3 (fanquake)
Pull request description:
Building Qt with Xcode 9.3 is currently broken with:
fontdatabases/mac/qfontengine_coretext.mm:775:20: error: qualified reference to 'QFixed' is a constructor name rather than a type in this context
1 error generated.
make: *** [.obj/qfontengine_coretext.o] Error 1
make: *** Waiting for unfinished jobs....
This patch should fix that, and will hopefully be the last time we have to patch Qt 5.7.
I've only made minor adjustments from the [original patch](https://codereview.qt-project.org/#/c/224900/), so that it will apply, although still not completely cleanly. We can cleanup if required.