[cairo] A new OpenGL backend for Cairo

[Luca Barbieri]

> Very interesting. Have you done any benchmarking to see what the
> performance is like?

On nVidia GeForce Go 7900GS using latest proprietary driver:

xrender - text: 398 frames in 5.0 seconds = 79.600 FPS
gl - text: 424 frames in 5.0 seconds = 84.800 FPS

xrender - composite: 226 frames in 5.0 seconds = 45.200 FPS
gl - composite: 46117 frames in 5.0 seconds = 9223.400 FPS

xrender - gradient: 425 frames in 5.0 seconds = 85.000 FPS
gl - gradient: 640 frames in 5.0 seconds = 128.000 FPS

xrender - trapezoids: 665 frames in 5.0 seconds = 133.000 FPS
gl - trapezoids: 1887 frames in 5.0 seconds = 377.400 FPS

xrender - text2: 8814330 glyphs in 5.0 seconds = 1762866.000 GPS
xrender - text2: 4114 frames in 5.0 seconds = 822.800 FPS
gl - text2: 15133230 glyphs in 5.0 seconds = 3026646.000 GPS
gl - text2: 7064 frames in 5.0 seconds = 1412.800 FPS

Best regards,
Luca Barbieri