Drop cloudabi

[kib]

Summary

According to https://github.com/NuxiNL/cloudlibc: CloudABI is no longer being maintained. It was an awesome experiment, but it never got enough traction to be sustainable.

There is no reason to keep it in FreeBSD.

[kib]

Finish cleanup. Pass tinderbox.

[emaste]

Sad to see it go, but indeed there is no value and ongoing cost to keep it in FreeBSD. Looks reasonable, although I did not check that there is nothing CloudABI-related left behind.

As an aside one interesting element that I'm still interested in is the ability for the process to start in capability mode; I'm curious how to support that independent of CloudABI. That's independent of this review though.

[kib]

In D31923#720728, @emaste wrote:

As an aside one interesting element that I'm still interested in is the ability for the process to start in capability mode; I'm curious how to support that independent of CloudABI. That's independent of this review though.

I am not sure what do you mean there.

If you enter cap mode and fork, child starts in the capability mode. If you mean 'how to start image in capability mode', execve from cap mode would do the same,

Semantic of SV_CAPSICUM is weird, it enters cap mode based on the image brand. We can do the same by elfctl flags, but I doubt that it is useful.

[kib]

Add ObsoleteFiles entry for cloudabi(4)