aco: Refactor hazard mitigations, separate pass for GFX10.

aco: Refactor hazard mitigations, separate pass for GFX10.

GFX10 hazards require a different approach compared to previous
generations, for example it doesn't need s_nop, and most hazards
can't be solved by adding NOPs at all. Also, they are not
resolved by branch instructions.

This commit reorganizes aco_insert_NOPs so that there is now a
separate pass for GFX10. The new GFX10 pass also respects the
control flow of the shader.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>