If the driver can't create a PIPE_FORMAT_R16G16B16A16_SNORM surface, create
an accum surface using a shallower format and taller height. Since only the
accum buffer code accesses the surface the actual format doesn't really
matter, just that there's enough memory.
We'll apply this function to GLSL vertex programs. In GLSL it's legal to
read and write varying (output) vars in a vertex shader. But reading from
an output register isn't supported by all hardware. This routine examines
the vertex program for that condition and rewrites it to use temporary
registers where needed.
Encode edgeflags (and reset_stipple info) into the top two bits of the
fetch elements. This info could be moved elsewhere, but for now we
can live with a 1<<30 maximum element size...
Also use the primitive decomposition code from draw_prim.c verbatim, as
it includes all this stuff and is known to work.
GLSL Vertex and fragment shaders now have independent parameter buffers.
A new gl_uniform_list is used to keep track of program uniforms and where
each uniform is located in each shader's parameter buffer.
This makes better use of the space in each buffer and simplifies shader linking.
Also, make sure that field is copied/updated in the program clone and combine functions.
Without this we weren't getting SAMP declarations in the TGSI shaders.
Also, implement support in the draw module. We were hardwiring these
to one for quite a long time...
Currently using a draw_set_edgeflags() function, may be better to push
the argument into the draw_arrays() function. TBD.
Previously all drivers were in twosided mode since they checked for
stencil.enable[1] flag which was a copy of stencil.enable[0]. Note that drivers
should not reference stencil[1] state (other than the enable) if twosided
stenciling is disabled (for now the stencil state is still copied but for
instance clear_with_quads won't provide useful values in there).
Also, use _TestTwoSide instead of TestTwoSide since results would be
bogus otherwise if using APIs with implicit two side stencil enable
(i.e. core ogl 2.0).
