Resolve implicit conversion error on latest MacOS Mojave with latest Xcode

[Bauer312]

This change pulls in the update made by jeremyhu in the upstream xhyve project with commit 9ea6650d3766c897ef85a3df15fdd9abcc9ee858 and resolves all implicit conversion errors reported in MacOS Mojave 10.14.4 with LLVM 10.0.1, as reported in issue #246

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "update-fbsd" git@github.com:Bauer312/hyperkit.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[Bauer312]

It appears as though the CI failure is coming from a recent homebrew update:

Error: opam: "cxx11" is not a recognized standard
Exited with code 1

Not sure of the proper way to proceed, except that this PR may need to wait before merging.

[ijc]

Thanks @Bauer312 the change looks good to me, although I don't really understand the three apparently identical commits, is it possible to squash them? If you could also add the error message to the ocmmit message at the same time that would be double awesome...

@djs55 looks like the Opam stuff broke CI again, can you take a look please.

[Bauer312]

@ijc I attempted to squash the commit but somehow there is another change showing. I am afraid that I mangled this PR quite badly. Perhaps this PR should be rejected and I should begin again from a fresh branch. I'm sorry to have taken so much of your time.

[ijc]

@Bauer312 I only see one commit right now and it seems good.

We just need to sort the CI issue, but that's really on us not you (unless you are super keen to dig into such things). I'll coordinate with @djs55 today.

[ijc]

@Bauer312 I hope #249 will solve the CI issue, I will let you know when you can rebase.

[ijc]

@Bauer312 right, #249 is merged and I think if you rebase onto current master CI will be green! 🤞

[townsend2010]

Any idea when this PR will get merged? It's been blocking some folks...

[Bauer312]

@ijc @townsend2010 I took care of the requested changes and believe that it is ready. Perhaps I should have posted a note that it was was ready. Sorry about that!

[townsend2010]

@Bauer312,

No worries! I just wanted to poke a bit to make sure it doesn't get lost:) Thanks!

[justincormack]

Sorry, @ijc is on holiday, LGTM.