mail-filter/spamassassin: new revision without the "bayes" USE flag.

mail-filter/spamassassin: new revision without the "bayes" USE flag.

In bug 617950, Deniss Gaplevsky asked that we add Redis support for
the SA bayes engine. I looked into it, and it turns out that the
support is already built-in. That makes things a little weird, because
it would have put us in the position of adding a "redis" USE flag that
does nothing.

Some background will hopefully clarify: when I took over as maintainer
of SA, you were required to choose one of USE="berkdb mysql postgres
sqlite". In other words, bayes support wasn't optional, and you had to
choose a database -- there was no "bayes" USE flag. I don't use bayes,
so I added the "bayes" flag to let me proceed without selecting a
database type.

If I had known about Redis at the time, a better solution would have
been to do what I just did: simply drop the REQUIRED_USE constraint
forcing you to choose one of USE="berkdb mysql postgres sqlite". That
is the end result of this commit, although I had to get rid of the
"bayes" flag now to make it all work.

Gentoo-Bug: 617950

Package-Manager: Portage-2.3.6, Repoman-2.3.1