mount: add remote-fs dependencies if needed after change

mount: add remote-fs dependencies if needed after change

This is an attempt to add it the remote-fs dependencies to a mount unit
if the options change, like when the utab options are picked up after
mountinfo has already been processed.  It just adds the remote-fs
dependencies, leaving the local-fs ones in place.

With this change I always get mount units with proper remote-fs
dependencies when mounted with the _netdev option.