Fixes <https://bugs.gnu.org/41607>.
Reported by Stephen Scheck <singularsyntax@gmail.com>.
* nix/libstore/gc.cc (LocalStore::deletePathRecursive): When we try to
move a dead directory into the trashDir using rename(2) but it returns
an EXDEV error, just delete the directory instead. This can happen in a
Docker container when the directory is not on the "top layer".