nv50,nvc0: always pull out bufctx on context destruction

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50: setup scissors on clear_render_target/depth_stencil

[imirkin: add logic to also clear the "regular" scissors]
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50,nvc0: handle guard band defines

[imirkin: moved default case out of switch]
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50,nvc0: allow 15,16,30 bpp display formats

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nvc0: use PRIxPTR for sizeof()

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nvc0: assert that we have vertex elements state

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50,nvc0: set constbufs dirty on pipe context switch

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50/ir/tgsi: TGSI_OPCODE_POW replicates its result

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50/ir/opt: fix constant folding with saturate modifier

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50/ir: fix lowering of predicated instructions (without defs)

Note that predicated instructions with defs are still not supported
because transformation to SSA doesn't handle them yet.

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50/ir/tgsi: optimize KIL

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50: count wrapped textures towards the tex_obj count

But don't count their size towards the allocated memory, since that
belongs to whoever created it.

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>