Merge topic 'fileapi-relative-under-root'

41be8cb44a FileAPI: Fix paths relative to root directory
3f7f2368d6 Avoid extra / in path to CMakeLists.txt in root directory

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !11314