Add config for building on windows

[cyberemissary]

This allows to build on windows in accordance to php build guide: https://wiki.php.net/internals/windows/stepbystepbuild_sdk_2

DISCLAIMER: Personally only tested on PHP 7.2, but this should work for all other version that this extension supports

[BitOne]

Thanks @cyberemissary for this work. My main problem is that I don't have access to a Windows environment. So I cannot maintain and support this configuration. Moreover, I cannot make sure that new development will not break this code. But Travis seems to have Windows support now: https://blog.travis-ci.com/2018-10-11-windows-early-release

Can you provide a changed in .travis.yml file with the right commands to build the extension and run the phpt tests? I have no idea what to do to compile it on Windows.

Thanks in advance !

[cyberemissary]

Although it compiles, it doesn't actually work on windows, Does not return any memory data.

I'll try go debug this, but don't know when I will have time. Once I figure it out i'll add the travis configs as well.