Adjust zed.d symlink-preservation

Closes BTS#983401.

 - Overwrite dangling symlinks on install
 - Does not clobber symlinks on removal

Signed-off-by: Antonio Russo <aerusso@aerusso.net>
(cherry picked from commit b024d59f5976ea75ac9a0b48612b7032d24513ee)
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>

debian/zfs-zed.postinst

@@ -8,7 +8,7 @@ etcd="/etc/zfs/zed.d"
 while read -r file ; do
     etcfile="${etcd}/${file}"
     [ -e "${etcfile}" ] && continue
-    ln -s "${zedd}/${file}" "${etcfile}"
+    ln -sfT "${zedd}/${file}" "${etcfile}"
 done < "${zedd}/DEFAULT-ENABLED"
 
 # remove the overrides created in prerm