Pruning Redux

[Warner Losh]

Greetings,

After feedback on my bug review, I've pushed the uncontested items, as well
as one or two common sense hacks that I believe will have good support.
There's one remaining item, which I'll get to at the end of this message.

I've gone ahead and removed the 32-bit kernel on 64-bit hardware
configuration files. They are no longer supported, but might happen to work.

I've removed the sibyte / BCM1250 subport.

I've removed the SENTRY5 config file.

I've removed the SMP versions of the Ingenic JZ4280 config files. This is
the CI20 board(s), but not the ones based on X1000 which are not SMP.
Rather than removing the port as initially discussed, I took this more
limited action.

I removed the gxemul support. It was great when we didn't run on qemu, but
it's time has passed.

I've stayed my hand on the MediaTek 2880 and Atheros AR531x removal. But
there's a catch. The former is complete and still builds. The latter is
incomplete and there's no way it could possibly build because the support
for it is not listed in any config file. I need patches to fix this
situation by February 1, 2019, or I'll remove the Atheros AR531x partial
support at that time. Not because of the need to have a mips32r2 core, but
because it has been disconnected for some time and nobody has noticed or
complained until I took a close look and threatened to remove it.

I've also implemented the atomic_swap_64 in a less optimal, but more
portable, way. I hope to circulate it for testing shortly. At that time,
the old CI20 config files will really break, but I thought it best to
communicate and document this happening in advance of it really happening.
Once *that* is in the tree, I'll go remove all the hacks we have in place
because mips didn't have the proper 64-bit ops.

Please let me know if you have feedback on this. thanks to all who provided
feedback on the first round.

Warner