bug#7357: csplit: memory exhausted when using stdout / pipe instead of a file

[Jim Meyering]

Voelker, Bernhard wrote:
> Jim Meyering wrote:
>>    src/csplit: <2GiB of spaces>xx<2GiB of 0's>: File name too long
>
> I'm not an expert at all in this, but isn't there PATH_MAX on every system?
> So the suffix format could be limited to `csplit -b %<PATH_MAX>d`.
> Just a thought...

On some systems (e.g., Hurd) PATH_MAX is not even defined.
ISTR that on others it is very large, like INT_MAX or UINT_MAX.
Where it is defined, we could do something like that.
Or even better, use a limit (again, if there is one) on the length
of a file name, taking into account where any "/" are in the expansion
of the format string.

Whatever we do, the simpler it is the better, since this is solely
to handle errors about ridiculously long file names.