This will allow us to use waffle with its upcoming WGL support for
Windows. With that done, the final step to removing glut is to convert
piglit to use waffle for MacOS.

Current implementation does not have input handling/event loop, and as
such one needs to pass "-auto" when running individual tests, otherwise
the test will abort after being displayed for 8 seconds.

Waffle 1.5.0 is the first version that has WGL support.

TODO:
 - Add input handling (event_loop).

v2: Updated the instructions in the README.
v3: Update against upstream Waffle (no API breakage)
v4: s/Sleep/fprintf()+getchar()/ in the event_loop. Suggested by Jose.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Brian Paul <brianp@vmware.com> (v1)