Intel Broadwell Graphics Are Much Faster With Mesa 11.3

Even with the very basic OpenArena game, Mesa 11.3-dev is running noticeably faster than Mesa 11.2 stable.

The open-source Tesseract game was also running much better on Mesa 11.3-dev for this HD Graphics 5500 Broadwell ultrabook/laptop.

Unigine Valley improved too, albeit it's still too much of a beast for running fluidly on Intel hardware.

Very significant performance improvements too for Xonotic...