Adding units to fallocate help message

[edneville]

No description provided.

[karelzak]

I understand the motivation, but I'm not sure about the implementation. First, we have many places in util-linux where is 'size' or 'offset' and where is possible to use size suffixes. It would be nice to keep all the --help outputs consistent.

Years ago someone suggested coreutils-like --help output:

Options:
  ...
  -o, --offset <num>   offset for range operations, in bytes

Where:
  <num> arguments may be followed by the multiplicative suffixes for  
        GiB, TiB, PiB, EiB, ZiB,  and   YiB (the "iB" is optional).

it means after Options add a new section "Where" with necessary details.

[edneville]

@karelzak, hopefully that's more consistent now.

[karelzak]

Looks cool, I'll merge it later this week or next. Thanks!

[karelzak]

I have consolidated it more to keep all in include/c.h only
f1970cc

Thanks!