i965g: clean up GEN7 PCB alloc
i965g: clean up GEN7 URB
i965g: clean up GEN7 GS
i965g: clean up GEN7 VS
i965g: clean up GEN7 SF/SBE
i965g: clean up GEN7 WM/PS
i965g: make GEN6/GEN7 GPEs function tables
i965g: expose GT to GPEs
i965g: limit number of VS URB entries in GPE

Also fix total size calculation.
i965g: assume D32_FLOAT in SF when there is no depth buffer
i965g: fix tgsi.const on GEN7

Send ld to sample the constant buffer.