cp: Use ahash

[oech3]

No description provided.

[oech3]

cp_large_file[16]
+1% 395.2 µs -> 389.8 µs

cp_archive_balanced_tree[(5, 4, 10)]
+1% 77.3 ms -> 76.5 ms

cp_recursive_wide_tree[(6000, 800)]
+1% 188.4 ms -> 187.1 ms

cp_recursive_deep_tree[(120, 4)]
+1% 13.5 ms -> 13.4 ms

cp_recursive_balanced_tree[(5, 4, 10)]
+1% 71.9 ms -> 71.5 ms

cp_preserve_metadata[(5, 4, 10)]
0% 74.1 ms -> 73.8 ms

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/date/date-locale-hour. tests/date/date-locale-hour is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cut/bounded-memory is no longer failing!
Note: The gnu test tests/cut/cut-huge-range is now being skipped but was previously passing.