i965/vec4: Make a function for setting up vec4 program key clip info.

This functionality will need to be reused by geometry shaders.
!UPSTREAM: i965/gs: make the state atom for compiling Gen7 geometry shaders.

TODO: maybe disentangle
!UPSTREAM: Primitive ID part 3
!UPSTREAM: i965/gs: Generalize some error messages for GS.

TODO: find more places to generalize.
TODO: Don't use "VS/GS" terminology.  Use "vec4" terminology, since that will endure longer.
i965/gs(gen7): Allocate URB space for use by geometry shader
!UPSTREAM: i965/gs(gen7): Allocate push constant space
i965/vs: generalize push const upload in preparation for GS
i965/gs: set up GS state
!UPSTREAM: Primitive ID part 4
!UPSTREAM: i965/vp: Keep track of the location of the first PROGRAM_STATE_VAR.

Previously, when compiling ARB vertex shader programs (and fixed
function vertex programs), we assumed that the first PROGRAM_STATE_VAR
was associated with the first element of the brw_vec4_prog_data::param
array.  However, in the patch that follows, we will need to allocate
space for clip plane uniforms before PROGRAM_STATE_VAR uniforms, so
that will no longer be true.

To prevent regressions, this patch records the location of the first
PROGRAM_STATE_VAR uniform, and uses that as an offset when processing
any ARB vertex program instruction that refers to a state var.

TODO: probably unnecessary for GLSL 1.50 style geometry shaders
!UPSTREAM: i965/gs: Assign clip plane uniform registers before emitting code.

The uniform registers for clip planes need to be assigned before we
try to emit the dot products that convert gl_ClipVertex into
gl_ClipDistance.

In vertex shaders the dot products are emitted by the call
emit_thread_end(), so it is safe to wait until just before that call
to set up the uniform registers for clip planes.  But in geometry
shaders, the dot products are emitted as we're traversing the IR
(since they happen during the shader's call to EmitVertex()).  So we
need to make sure the uniform registers are set up before then.

TODO: probably unnecessary for GLSL 1.50 style geometry shaders
!UPSTREAM: i965: turn on GS

TODO:
- Commit message
i965/gen7: Allow URB_WRITE channel masks to be used.

Previously, brw_urb_WRITE() would unconditionally override the channel
masks in the URB_WRITE message to 0xff (indicating that all channels
should be written to the URB).

For geometry shaders, we need the ability to set the channel masks
programatically, so create a flag to prevent brw_urb_WRITE() from
overriding them.
!UPSTREAM: i965/gen7: Add the ability to send URB_WRITE_OWORD messages.

This will be used by geometry shaders to implement EndPrimitive()
functionality.

TODO:
- Move to appropriate place in series.
!UPSTREAM: i965/gs: implement EndPrimitive() functionality.

Stuff that needs fixing:
- Probably should pack vertex_count and cut_bits into a single register
- Code should be conditioned on whether the shader uses EndPrimitive()
i965/gs: Fixup gl_PointSize on entry to geometry shaders.

gl_PointSize is stored in the w component of VARYING_SLOT_PSIZ, but
the geometry shader infrastructure assumes that it should look for all
geometry shader inputs of type float in the x component.  So when
compiling a geomtery shader that uses a gl_PointSize input, fix it up
during the shader prolog by moving the x component to the w component.

This is similar to how we emit fixups and workarounds for vertex
shader attributes.
!UPSTREAM: vbo: Update vbo_count_tessellated_primitives for new primitive types.

TODO: test.
!UPSTREAM: i965: Add new primitive types.

TODO: test.
!UPSTREAM: Debug optimization passes
i965/gs: Support UBOs by generating surface state and binding tables.

All but two of the piglit GLSL 1.50/uniform_buffer tests work, and
maxuniformblocksize and referenced-by-shader work.