Include link counts and inode numbers in metadata dumps.

Include link counts and inode numbers in metadata dumps.

When the link count on a file is greater than one, include the link count
and a representation of the inode number (actually, inode number and
device).  This will provide all information which should be needed for
detecting hard links at restore time.  The backup program itself does not
identify hard-linked files and treat them any differently--since storage
for identical files can be shared, the storing a hard-linked file multiple
times should still be relatively efficient.