labelsmeta is now compressed with gzip
...for those unfortunates on systems incapable of dealing with files >2GB
but also want to convert a CVS repository that generates label data in
excess of that.
The number of people with this problem should be small: realistically,
this will only be useful for those people whose Perl installations can't
pipe out to 2GB sizes, but can run a p4d that can run db.* files >2GB.