Add a test for previous octal/string filemode fix.
Add a test for previous octal/string filemode fix.

Apparently nothing was testing symlink behaviour; add a basic test for
symlink save/restore.

Signed-off-by: Avery Pennarun <e03ccfb89d416c4697ad6970ce86a92c1c28a78e@gmail.com>

jbaber/bup,mhoeher/bup,pombredanne/bup,ToxicFrog/bup,tjanez/bup,apenwarr/bup,jbaber/bup,jbaber/bup,pombredanne/bup,ToxicFrog/bup,mhoeher/bup,pombredanne/bup,jbaber/bup,pombredanne/bup,mhoeher/bup,mhoeher/bup,tjanez/bup,gevaerts/bup,mhoeher/bup,tjanez/bup,tjanez/bup,ToxicFrog/bup,gevaerts/bup,pombredanne/bup,pombredanne/bup,apenwarr/bup,tjanez/bup,jbaber/bup,apenwarr/bup,gevaerts/bup,jbaber/bup,gevaerts/bup,apenwarr/bup,ToxicFrog/bup,tjanez/bup,ToxicFrog/bup,mhoeher/bup,gevaerts/bup