Value of old "vendor" branches vs. linear history

[Ulrich Spörlein]

Dear all, I'm running out of things to do for the conversion, so I'm
looking at streamlining some of the history in the repo.

Please see https://github.com/freebsd/git_conv/blob/master/history.md
for some of the examples as well as before and after pictures (use the
links to see the colorized version, which is easier to follow).

So unless someone objects and can convince me that `vendor/unknown` or
`unlabeled-1.1.1` branches must be represented as they currently are in
SVN , I'll go forward with this and splice in these commits directly into
the mainline, where feasible.

I think this will mostly affect:
- vendor/games/dist
- vendor/unknown
- cvs2svn/branches/unlabeled-x.y.z
- vendor/misc-GNU/dist
- vendor/CSRG/dist and vendor-crypto/eBones/dist

and potentially parts of vendor/NetBSD/dist and vendor/OpenBSD/dist. As
well as numerous one-off cvs2svn/branches/foo "branches" (or rather
random CVS import tags).

Cheers
Uli