removing filesystems/perfuse soon

[Greg Troxel <gdt%lexort.com@localhost>]

(manu@ and I have discussed this and agree on the plan.)

Recall that for FUSE, NetBSD has puffs(4) kernel interface, while the
Linux world expects to use libfuse (filesystems/fuse{,3}) which then
talks to /dev/fuse.  On NetBSD we have perfused(8) which provides a
socket /dev/fuse, and talks to puffs.  Most FUSE filesystems use the
high-level FUSE API, which on NetBSD is available in refuse(3), a
library that talks to puffs.  One, fuse-ntfs-3g, needs to use libfuse,
and one, glusterfs, talks to /dev/fuse directly.

Everything about perfused is NetBSD only because it interfaces with
puffs(4) which only exists on NetBSD.

perfused exists in two places:

  - Base NetBSD system as /usr/sbin/perfused.  It was added in NetBSD 6,
    released October 2012.

  - pkgsrc/filesystems/perfuse.  If you bl3 this, it will use the
    builtin on NetBSD 6+, and on NetBSD <5, will build perfused from
    sources.  Puffs was only stable in 5.

Some packages that need perfused bl3 on filesystems/perfuse, and some
don't.

Dropping filesystems/perfuse, it will no longer be possible with current
pkgsrc to build/use libfuse{,3}, glusterfs, and fuse-ntfs-3g for NetBSD
5.  That's the only impact.  Earlier NetBSD wouldn't work now, and 6+
will be exactly as it is now.

pkgsrc formally supports only NetBSD 9 (for I hope a very short time)
and NetBSD 10, and less formally also 11 and current.  We don't like to
gratuitously break somewhat older versions, like 8 and 7.  But the idea
that somebody is running glusterfs on NetBSD 5, and wants to keep
updating to new pkgsrc branches and is otherwise finding that things in
pkgsrc build and owrk ok, is just not credible.  So I expect that zero
people are affected.

I'm going to start removing the glusterfs bl3 line from packages that
have it now, and I'll remove the perfuse package in a few days.