[Mesa-dev] RFC: egl/gallium: implemlent EGL_KHR_create_context.

[Knut Andre Tidemann]

Here is my go at implementing the EGL_KHR_create_context extension for the
gallium state tracker. I'm new to Mesa development, so excuse me if I have
forgotten something.

This brings the EGL_KHR_create_context extension to the gallium egl state 
tracker. It is requried to create Core profile contexts from egl.

This passes the same amount of piglit tests as the intel driver (18/21, the 
OpenGL ES 3.0 is skipped). Some of the failures seems to be inconsistencies
between the returned error codes and what piglit expects. This comes from the
core egl implementation in Mesa.

I have only tested this on the r600g driver, but there are no changes on
the driver level.