nir/linker: Add a pure NIR implementation of the atomic counter linker

This is mostly just a straight-forward conversion of
link_assign_atomic_counter_resources to C directly using nir variables
instead of GLSL IR variables.

It is based on the version of link_assign_atomic_counter_resources in
6b8909f2d1. I’m noting this here to make it easier to track changes
and keep the NIR version up-to-date.

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/compiler/glsl/gl_nir_linker.h

@@ -40,6 +40,9 @@ void gl_nir_set_uniform_initializers(struct gl_context *ctx,
 void nir_build_program_resource_list(struct gl_context *ctx,
                                      struct gl_shader_program *prog);
 
+void gl_nir_link_assign_atomic_counter_resources(struct gl_context *ctx,
+                                                 struct gl_shader_program *prog);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif