Replicate the structure of an original directory-tree and populate the replica with symlinks to the original directory-tree.
This is useful when the original directory-tree is not writable by the user.
It handles the case where the original directory-tree has a relative symlink within the tree.
$ mkdir $TOP_OF_REPLICA
$ cd $TOP_OF_REPLICA
$ graft $TOP_OF_ORIGINAL
$ cargo build --release