CIFS: Deprecating NFS mounting syntax in mount.cifs

[scott.lovenberg at gmail.com]

This patch adds a warning when using NFS mounting syntax (server:/share), instead of the usual UNC syntax (//server/share || \\server\share), that support for NFS style mounts will be removed in version 6.0 of the mount.cifs utility.

The reasoning for this is simple.  Support for NFS syntax is undocumented and increases maintenance overhead.  This came up recently on the cifs-utils list when discussing how to handle mounting a share NFS style using an IPv6 address. Since the ':' character is valid in a POSIX file path or share name it is an ambiguous delimiter.  Consider the following valid server share : "dead:beef::1:iSCSIExportedByIQN:storage".

Instead of adding complicated code to the parser to support an undocumented feature, we're optin
g to remove the feature in the mount utility in version 6.0 if there is no objection.