[Piglit] Windows builds w/ Appveyor

[Jose Fonseca]

Hi Dylan,


I've been working on getting Piglit windows builds automated with 
Appveyor.  (I've been maintaining an internal Jenkins server for this, 
but I want to get out of that business for open-source projects.)


I got Piglit to build with MinGW + FreeGlut:

   https://cgit.freedesktop.org/~jrfonseca/piglit/log/?h=appveyor
 
https://ci.appveyor.com/project/jrfonseca/piglit-fc01r/build/job/ksgcs78o6crpgw2f

And I plan to later get it to build with Waffle and upload binaries 
somewhere.



However, I just moved aside your initial appveyor.yml to simplify 
things.  So I'd like to hear from you how to integrate both things

Part of the issue is that it doesn't run successfully:

 
https://ci.appveyor.com/project/jrfonseca/piglit-fc01r/build/appveyor-1/job/rf1upre1k9awji4c

I also don't think it's necessary to support Python 2 with Windows -- 
it's just as simple to install Python 3 and its dependencies --, and 
this way we don't need to worry about two.

Let me know what you think.



Also, for the record, I'm personally not too worried about MSVC.  In 
fact I think that supporting only MinGW should be acceptable.   I can 
try to add MSVC support to Appveyor too if people prefer to have it 
around.  One way or the other, once the AppVeyor integration is done, 
I'm hoping to keep my hands off.


Jose