[foundation] Do not assign a nullptr to stding if ROOTSYS is unset.
[foundation] Do not assign a nullptr to stding if ROOTSYS is unset.

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