st/nir: use NIR for asm programs

st/nir: use NIR for asm programs

This uses prog_to_nir to translate ARB assembly programs to NIR.

Co-authored by Tim Arceri, Dave Airlie, and Ken Graunke:

 - [Tim Arceri]: original patch
 - [Dave Airlie]: fix crashes with parameter names
 - [Ken Graunke]:
   - Rebase on SCALAR_ISA cap, lower wpos_ytransform too.
   - Rebase on streamout fixes.
   - Lower system values for fragcoord support.
   - Don't try to use prog_to_nir for ATI_fragment_shader programs.
   - Create TGSI for fixed-function or ARB vertex shaders even if the
     driver prefers NIR, so we can create draw module shaders for
     feedback/select emulation, which rely on TGSI.

Tested on:
- iris (Intel Skylake/Kabylake): Piglit & GL CTS - Ken Graunke
- radeonsi (AMD Vega 64): Piglit - Ken Graunke
- vc4/v3d - Piglit - Eric Anholt
- freedreno - dEQP - Kristian Høgsberg

Fixes lit_degenerate_case on vc4 and v3d, and vp-address-01,
vp-arl-constant-array-huge-offset-neg, and vp-arl-neg-array on v3d.
No Piglit regressions on radeonsi; no dEQP regressions on freedreno.

Acked-by: Eric Anholt <eric@anholt.net>
Tested-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>