nir: Add a pass for gathering various bits of shader info

Reviewed-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir.h

@@ -2187,6 +2187,7 @@ bool nir_lower_locals_to_regs(nir_shader *shader);
 
 void nir_lower_outputs_to_temporaries(nir_shader *shader,
                                       nir_function *entrypoint);
+void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
 
 void nir_assign_var_locations(struct exec_list *var_list,
                               unsigned *size,