Crash when pasting large and slow data

When copy-pasting large text buffers to a Qt5 application using the Wayland backend, if the source of the copy-paste operation writes enough data and in small enough chunks, (e.g., because the source application must read from a network, or compute something for each line of copied text), then the application being pasted into can crash.

The cause is a stack overflow in the function QWaylandMimeData::readData, which recursively makes successive calls to read() instead of using a while loop.

Based on git history, can happen for versions from 5.4 until now.