QQuickItemView: Fix model creation

In setDelegate(), we want to create the model if it doesn't exist, not
if it's not ours. Otherwise we might overwrite a perfectly fine model
set by user code when creating a delegate.

Also warn when we cannot retain an explicitly set delegate because an
incompatible model was passed.

Pick-to: 6.9 6.8
Change-Id: I43635d4cc2fcd0f539e1cfdf742a7d941323c2fe
Reviewed-by: Shawn Rutledge <[email protected]>
Reviewed-by: Fabian Kosmale <[email protected]>

0 files changed, 0 insertions, 0 deletions