Merge topic 'project-vars' c5f7e3bc3b Merge branch 'backport-project-vars' into project-vars 86ad7cc886 project: Only define non-cache vars if already defined 4c152752da Help: State valid scopes for using proj_SOURCE_DIR and proj_BINARY_DIR Acked-by: Kitware Robot <kwrobot@kitware.com> Acked-by: buildbot <buildbot@kitware.com> Merge-request: !9820