The minimum CMake version for Qt6 is 3.16, so all the calls to
cmake_minimum_required() are updated here to enforce that
minimum. This will avoid any CMake version-related warnings
from Qt.
Avoid hard-coding Qt5 where the tests could now be using
Qt5 or Qt6.
Fixes: #22188
For Qt >= 5.15.0 and Ninja generators AutoMoc creates a depfile to let
Ninja decide when to run AutoMoc. This was introduced by commit aebfbcaa46
(AutoGen: Use depfiles for the XXX_autogen ninja targets, 2020-01-14,
v3.17.0-rc1~58^2).
However, AutoMoc was not triggered after adding a new moc-able file to
the project. This patch adds the project file (and potentially included
files) to the dependencies in the depfile.
Now, a re-run of AutoMoc is triggered if the project file changes.
Fixes: #21127