Don't try to get HSM status in non-HSM filesystems

Return simple 'r' (regular file) if the filesystem is not
under HSM. Before it was tried to fork a command which in this
case couldn't work. Thanks to Christof Hanke...
Check free blocks only if not an OSD volume

During 'vos move' free blocks on the target partition are compared
do used_blocks of the volume. Makes sense only if data will be really
stored there. Thanks to Christof Hanke...