- improve munging of NetBSD.dist and METALOG into metalog, using mtree to
"cleanup" / "merge" entries, and don't sort the result.
relies upon mtree to not change the order (see below)
- use (newly added) join.awk to output lines in metalog that are listed
in flist.${set}. join.awk doesn't require either file to be sorted
(unlike join(1)), which is required because we want to retain the
order of the metalog, because certain entries in the metalog (such
as hard links) make assumptions about the permissions of earlier entries.
this should fix [toolchain/16207]