Combining NOT_FOR_* and BROKEN_ON_*

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

We currently have two settings to disable packages for particular
platforms:

NOT_FOR_* for packages where it "doesn't make sense" for them to be
built on a platform, and BROKEN_ON_* for packages where it does, but
they don't build for some reason.

I understand the difference between the two, but I don't see it as a
useful difference to make - the result is the same, we don't try
building on that platform.

It also has lead to a couple discussions already if one or the other
is more appropriate for a particular package, none of which I remember
as being useful.

Why? Because a useful outcome would be that someone fixes a BROKEN_ON
package.

I don't remember a single commit (but there must have been some) where
a BROKEN_ON package was fixed, but I remember at least three recent
discussions about which of the two variables should be set.

To avoid the not very useful discussions, I suggest removing either of
them; probably BROKEN_ON_*, but I don't really care.

Comments?
 Thomas

(the same for BROKEN_EXCEPT_ON and ONLY_FOR)