close_range: add audit support

[arichardson]

Summary

This fixes the closefrom test in sys/audit.

Includes cherry-picks of the following commits from openbsm:

https://github.com/openbsm/openbsm/commit/4dfc628aafe589d68848f7033f3d3488c4d979e0
https://github.com/openbsm/openbsm/commit/99ff6fe32aebc5a4b8d40d60062b8574697df557
https://github.com/openbsm/openbsm/commit/da48a0399e95448693d3fa2be48454ca564c1be8

[arichardson]

The contrib update should probably be a vendor import instead of part of this commit, but I've included in the revision to make it obvious what needs to change.

[kevans]

Ah, damn, I had staged this in D24553 but failed to follow through. I like cmd better, though, since hifd will most often not be a valid fd. I'll take a closer look in a bit

[arichardson]

@kevans should I do the openbsm vendor update or will you do it?

[kevans]

In D28388#635536, @arichardson wrote:

@kevans should I do the openbsm vendor update or will you do it?

I think @gbe actually has it staged or nearly there, so I'll defer to him on that (and CC here for awareness)

[arichardson]

ping? Should I commit this as is or continue waiting for a contrib/openbsm update?