possible bug in 'sum' command, with a demo

[Kang-Che Sung]

> I can't reproduce the same result in the latest BusyBox version from git.
> Perhaps this has been fixed already?

Oops. My mistake. Used the wrong input. Here's the corrected one:

    $ printf '145146\n\n'| ./busybox cksum
    1560277601 8
    $ printf '145146\n\n'| cksum
    1560277601 8
    $ printf '145146\n\n'| ./busybox sum
    59944     1
    $ printf '145146\n\n'| sum
    59944     1
    $ printf '107108\n\n'| sum
    59944     1
    $ printf '107108\n\n'| ./busybox sum
    59944     1
    $ printf '107108\n\n'| cksum
    2984653705 8
    $ printf '107108\n\n'| ./busybox cksum
    2984653705 8
    $ ./busybox | head -n 1
    BusyBox v1.26.0.git (2016-09-23 07:33:08 CST) multi-call binary.
    $ sum --version | head -n 1
    sum (GNU coreutils) 8.21
    $ cksum --version | head -n 1
    cksum (coreutils) 8.21