Add optional dependency for on p11-kit for gnutls

[toonetown]

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After the discussion and comment at #5390 (comment), this PR adds an optional dependency on p11-kit. Similar changes are included within #5416, however, this change is limited to JUST gnutls.

[tschoonj]

I already did this in PR #5416

[toonetown]

@tschoonj
I already did this in PR #5416

Yes - I mentioned that...however, that change is a modification of multiple formulas - while this change is just a modification of gnutls. IMO, it is nicer to have them separated out into different commits/PRs (but the homebrew maintainers may disagree with me on that...in which case, they can close this one)

[tschoonj]

If you don't to wait until my PR is merged in, you could also use brew pull to get the changes.

[DomT4]

Blocked on resolution of #5434 and/or 46be01e.

[toonetown]

Closing this one in favor of #5416 (which apparently has this change as well)

[fdelapena]

@toonetown it looks like #5416 removed p11-kit dependency before merging. Could you reopen this pull request?

[toonetown]

If this is appropriate and accepted, the "Do Not Merge" tag may need to be removed (I don't have permissions to change tags)

[toonetown]

This pull request is with an "optional" dependency on p11-kit - however, given the comment at #5390 (comment), maybe we should make it a recommended option?

@nmav
As the maintainer of gnutls, I'd strongly suggest making the p11-kit variant the default. The PKCS#11 functionality is essential in modern gnutls versions, especially for primary platforms like OSX which you would like your users to use smart cards, HSMs and the keychaintoken.

[toonetown]

Do I bump the "revision" in this formula for a change like this? I would guess the answer would be "yes" if we were to make p11-kit :recommended and "no" if we leave it as :optional. Is that correct?

[MikeMcQuaid]

Cross-posting from #8274 (comment):

Re: gnutls itself: given the gnutls maintainer has strongly recommended we make it on-by-default I'm fine with doing that, too, now. If we do so it'd be good to also figure out how to include and enable the p11-kit macOS keychain integration you mentioned, too.

If it's :recommended (or even not an option at all) then, yeh, we probably want a revision bump.

[toonetown]

@MikeMcQuaid
If we do so it'd be good to also figure out how to include and enable the p11-kit macOS keychain integration you mentioned, too.

I will investigate this more and possibly submit a separate PR.

[toonetown]

I have updated this PR with the dependency as :recommended. If this is acceptable, could we get the do not merge tag removed, and get it reviewed for possible inclusion?

With this change, then change in #8274 is no longer needed.

[MikeMcQuaid]

Thanks for your contribution to Homebrew and patience with us here! Without people like you submitting PRs we couldn't run this project. You rock!

For future reference the preferred commit message format is gnutls: add recommended p11-kit dependency.. Please complete the issue template in future PRs where this format is detailed in the linked Contributing guidelines. Thanks!