[jayhemnani9910]

-n/--bytes only takes a plain number, so anything with a unit fails before comparing:

$ head -c 3000 /dev/zero > z1; cp z1 z2; printf '\1' | dd of=z2 bs=1 seek=1500 conv=notrunc status=none
$ diffutils cmp -n 1K z1 z2; echo $?
cmp: invalid --bytes value '1K'
2
$ /usr/bin/cmp -n 1K z1 z2; echo $?    # GNU cmp 3.12
0
$ /usr/bin/cmp -n 2K z1 z2
z1 z2 differ: byte 1501, line 1

GNU cmp takes the same suffixes for --bytes as for --ignore-initial, and the code already knew it (the TODO on the 1K test, and the comment on BytesLimitU64 about limits like 1Y).

The --ignore-initial parser becomes parse_size, which takes the option name for its error message. --bytes uses it, and parse_skip is now a thin wrapper, so its callers don't change. The test that expected --bytes=1K to fail now checks -n 1K, --bytes=1kB and --bytes=2M, and keeps a failure case for 1x.

Tests: the new cases fail on main. cargo test: 285 passed, same as main. cargo fmt --check is clean, and cargo clippy --all-targets gives the same warnings as on main. Against GNU cmp 3.12 with those two files, -n with 1K, 1kB, 2K, 1M, 1500K, 1T, 1Y, 1500 and 1499 gives the same result and exit code. 1b, 1x, 1Ki and -1 give the same error. GNU also takes 1k, 1KB, 1KiB and hex, and reads a leading 0 as octal, for both options; this parser does neither (it reads 010 as ten), and I left that for a separate change.

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