gallium/compute: Add PIPE_COMPUTE_CAP_IR_TARGET v4

v2: Tom Stellard
  - Update CAP description

v3: Tom Stellard
  - TGSI targets should pass an empty string for this CAP.

v4: Tom Stellard
  - TGSI targets can ignore this CAP.

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
2 files changed