blame: use "goto cleanup" for cleanup_scoreboard()

Amend a freeing pattern added in 0906ac2b54 (blame: use changed-path
Bloom filters, 2020-04-16) to use a "goto cleanup", so that we can be
sure that we call cleanup_scoreboard().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/blame.c

@@ -1167,7 +1167,7 @@ parse_done:
 	if (!incremental)
 		setup_pager();
 	else
-		return 0;
+		goto cleanup;
 
 	blame_sort_final(&sb);
 
@@ -1201,6 +1201,7 @@ parse_done:
 		printf("num commits: %d\n", sb.num_commits);
 	}
 
+cleanup:
 	cleanup_scoreboard(&sb);
 	return 0;
 }