Report the sky reserved-word count in the test output

20 of 149 sky sub-objects carry a non-zero word where the other 129 are zero,
so the reserved area is not uniformly padding. Reporting it rather than
asserting it, and clearing three clippy warnings from the unused counter.

crates/gc-extract/tests/disc.rs

@@ -2462,8 +2462,7 @@ fn sky_sub_objects_parse_on_every_level() {
     assert!(levels >= 20, "only {levels} levels had a sky region");
     assert!(total >= 100, "only {total} sky sub-objects parsed");
     eprintln!(
-        "sky: {total} sub-objects over {levels} levels; \
-         count {}..={}, width {}..={}, radius {:.2}..={:.2} on {nonzero_radius}",
+        "sky: {total} sub-objects over {levels} levels; count {}..={}, width {}..={}, radius {:.2}..={:.2} on {nonzero_radius}, {reserved_nonzero} with a non-zero reserved word",
         counts.0, counts.1, dims.0, dims.1, radii.0, radii.1
     );
 }