[cxxmodules] Give priority to local to the module headers to avoid cycles.
[cxxmodules] Give priority to local to the module headers to avoid cycles.

Resolves what's discussed in root-project/root#3392

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