JDK 9 RFR of JDK-8136738: InputStream documentation for IOException in skip() is unclear or incorrect

[Pavel Rappo]

> On 3 Jun 2016, at 19:30, Bernd Eckenfels <ecki at zusammenkunft.net> wrote:
> 
> It is unclear to me if this is really forbidden in the interface or in
> any implementation. With FileInputStream skip(-5) works.

Don't mistake `seek` for `skip`. `skip` can be implemented using `read`, but
may be using `seek`.

Here's the API point of view:

    * If {@code n} is
    * negative, the {@code skip} method for class {@code InputStream} always
    * returns 0, and no bytes are skipped. Subclasses may handle the negative
    * value differently.

Thanks,
-Pavel