nir: Add compute shader shared variable storage class

Previously we were receiving shared variable accesses via a lowered
intrinsic function from glsl. This change allows us to send in
variables instead. For example, when converting from SPIR-V.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir_validate.c

@@ -1047,6 +1047,11 @@ nir_validate_shader(nir_shader *shader)
      validate_var_decl(var, true, &state);
    }
 
+   exec_list_validate(&shader->shared);
+   nir_foreach_variable(var, &shader->shared) {
+      validate_var_decl(var, true, &state);
+   }
+
    exec_list_validate(&shader->globals);
    nir_foreach_variable(var, &shader->globals) {
      validate_var_decl(var, true, &state);