iOS: Investigate Qt6 crash & update afterwards

[hoffie]

Finally found out (again) how to view iOS crash logs.
You need macOS and The console App.
I think that's the error:

We probably need to change the application class.
Or maybe https://forum.qt.io/topic/82102/can-t-create-qapplication-for-ios-using-cmake-build

Originally posted by @ann0see in #2300 (comment)

(Also see further investigation by @pljones in that ticket)

Original commit (including a relevant workaround) for reference: de632f4

[hoffie]

See #2625 (comment):

QMAKE_LFLAGS += -Wl,-e,_qt_main_wrapper

Thanks to @danryu.

[pljones]

@hoffie any progress on this?

[ann0see]

I think the GUI gets messed up with QT 6.