mv: gnu test case `part-hardlink` compatibility

[matrixhead]

This GNU test checks that when mv moves files between partitions, it preserves the hard links.

for example

mkdir dir
touch dir/file
ln dir/file dir/link
mv dir /dev/shm
ls -i /dev/shm/dir

in gnu's implementation, this would give us something like

5018 file  5018 link

notice the inodes are the same, but in uu-mv the inodes would differ