PHP 7.3 support

[fabiang]

Please make this extension compile with PHP7.3.

Current error with latest RC is:

php_memcached.c: In function 'zim_Memcached___construct':
php_memcached.c:1284:20: error: lvalue required as left operand of assignment
   GC_REFCOUNT(&le) = 1;

[NoiseByNorthwest]

You must currently checkout master, the patch is not yet released. 8bfdbcc

[sodabrew]

PHP 7.3 isn't GA yet, but it is getting into late betas, so I'll see about getting a release out for public use with the betas or at least 7.3-rc's.

[andrerom]

@sodabrew anything we can help with for getting a 3.1.0RC1 out? Like:

• Help review open PR's? Windows and Zlib change looks ok but any additional testing that should be done on any of them?
• For your own open PR, you need someone to take over for rebase on that?

[ryandesign]

PHP 7.3.0 final is out. Can you make a new release of php-memcached now?

[sodabrew]

Yep, I saw the release. I've been trying to get some of the dependencies updates, in particular https://github.com/msgpack/msgpack-php but nobody's home there. I suppose I can just make this a release note.

[mokraemer]

would be great if you have a least a alpha/beta release, so I can prepare the packages for distro release.

[derickr]

This currently is also a blocker for Travis: https://travis-ci.community/t/please-add-php-7-3-on-xenial/1238/13?u=derickr