Faithfully link symlinks even when they're broken

This little change prevents `linkRecursivelySync` from crashing if it encounters a broken symlink. This is relevant to me because Emacs creates broken symlinks as part of its file locking scheme, which can crash `ember server`. 

The resulting behavior is consistent with the way `linkRecursivelySync` is already intended to work: it just faithfully `link(2)`s every symlink it encounters, whether it's broken or not.