[waffle] Some new and old fixes

[Emil Velikov]

Hi all,

After respinning the latest changes (and ripping out WGL as it requires some
api/abi changes) here is a lovely list of fixes that gets us closer to building
waffle with mingw/msvc.

The first four patches are old (three cgl fixes that Chad would like to test
prior to pushing them + a patch from Chad).

Then a few misc fixes (not related to win32/mingw/msvc) followed by the addition
of c99_compat header (inspired by mesa) and a couple of third_party util libs.

The last 13 or so patches cover msvc quirks where it should work but instead
it dies agony.

Please give the series a look and/or bash.

Currently is available at https://github.com/evelikov/waffle in the
for-upstream-3 branch.


Cheers,
Emil