Use COMPILE_FLAGS rather than INCLUDE_DIRECTORIES property
Use COMPILE_FLAGS rather than INCLUDE_DIRECTORIES property

The INCLUDE_DIRECTORIES property only became available in
CMake 3.11, so we have to use COMPILE_FLAGS instead, which
is already available in our required version (CMake 3.4.3).

root-mirror/root,olifre/root,karies/root,olifre/root,karies/root,root-mirror/root,karies/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,karies/root,karies/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,karies/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,olifre/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root