Instead, a new pipe_transfer object has to be created and mapped for
transferring data between the CPU and a texture. This gives the driver more
flexibility for textures in address spaces that aren't CPU accessible.
This is a first pass; softpipe/xlib builds and runs glxgears, but it only shows
a black window. Looks like something's off related to the Z buffer, so the
depth test always fails.
allows the driver to overwrite buffer allocation, first step on the way
to making winsys interface internal to the drivers. state trackers and
the code above it will go through the screen
This will allow creating textures before a rendering context exists, for example.
Only implemented in i915 driver for now. i915pipe->texture_create() just
dispatches through to the i915screen->texture_create() to avoid state tracker
changes for now.
