shadow_copy2_realpath() snapshot path component removal

[David Disseldorp]

Hi Volker,

As part of the shadow_copy2 module rewrite, logic was added to remove
any snapshot component (e.g. @GMT-1984...) from the path returned by the
realpath VFS hook.

Do you recall whether there was something at a protocol level that
required this behaviour, or was it done to avoid wide link checks
so that snapshots could reside outside of the base share?

Cheers, David