Fixes for older macOS

[barracuda156]

This PR is based on patches used in Macports for building libuv: https://github.com/macports/macports-ports/tree/master/devel/libuv/files

P. S. I am bringing R packages into Macports now, and httpuv among them, and we want everything to build on Leopard up; it is desirable to have it fixed with upstream rather than keep carrying our local patch.

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[wch]

What versions of MacOS does this provide support for? The highest version I see reference to in this PR is MAC_OS_X_VERSION_MAX_ALLOWED >= 1070, and I believe that's for OS X 10.7, which last had a release 10 years ago.

It would be preferable if you could get the changes into libuv. We periodically update the copy of libuv bundled with httpuv, and it wouldn't be a good use of our time to be maintaining libuv patches for these old OS versions.

[barracuda156]

@wch As for OS X versions, everything from 10.4.11 up is still used, and specifically 10.5.8 is used quite a bit, since that is the last official release supporting PPC.
However I agree, that if you just borrow the code from libuv, then you face the same problem as we do with carrying patches – and it won’t be a Pareto improvement :)

I will try to find out what happened with submission of those to libuv upstream. If no one tried for w/e reason, I can try that.

[barracuda156]

@ryandesign Ryan, may I ask if you know whether our patches to libuv were submitted to upstream? Or should I try that?
At least two R packages are broken without those, and understandably it is preferable to have libuv itself fixed rather than carrying patches, if that works.