AutoMoc: Restore support for re-running after project file changes
Traditionally, AutoMoc was triggered on every build, but for Qt >= 5.15.0 and Ninja generators AutoMoc creates a depfile to let Ninja decide when to run AutoMoc.
In this scenario AutoMoc was not triggered if a new moc-able file was added to the project file. This patch adds the project file to the depfile in order to re-run AutoMoc if the project file changes.
Fixes: #21127 (closed)
Backport: release
Topic-rename: automoc-depend-project-file