Don't use dsync to de-dup files

The deduplication causes all files to get new mtimes in each round.
This forces rsync on each mirror to re-download the files and fix all
the hard-links.

Currently the archive shows about 4GiB of files in pool/ that have been
de-duplicated.  Most of the others are part of the installer or by-hash.

config/debian/dinstall.functions

@@ -430,7 +430,6 @@ function mkchecksums() {
         cd "$archiveroot"
         ${bindir}/dsync-flist -q generate $dsynclist --exclude $dsynclist --md5
         ${bindir}/dsync-flist -q md5sums $dsynclist | gzip -9n > ${md5list}.gz
-        ${bindir}/dsync-flist -q link-dups $dsynclist || true
     done
 }