util: rename list_empty() to list_is_empty()

This makes it clear that it's a boolean test and not an action
(eg. "empty the list").

Reviewed-by: Eric Engestrom <eric@engestrom.ch>

src/compiler/nir/nir_clone.c

@@ -629,7 +629,7 @@ fixup_phi_srcs(clone_state *state)
          list_addtail(&src->src.use_link, &src->src.reg.reg->uses);
       }
    }
-   assert(list_empty(&state->phi_srcs));
+   assert(list_is_empty(&state->phi_srcs));
 }
 
 void
@@ -669,7 +669,7 @@ clone_function_impl(clone_state *state, const nir_function_impl *fi)
    clone_reg_list(state, &nfi->registers, &fi->registers);
    nfi->reg_alloc = fi->reg_alloc;
 
-   assert(list_empty(&state->phi_srcs));
+   assert(list_is_empty(&state->phi_srcs));
 
    clone_cf_list(state, &nfi->body, &fi->body);