when used on platforms that actually define ioctl as taking an unsigned long.
(the BSDs and OS X / Darwin)

Adds a unittest for fcntl.ioctl that tests what happens with both positive and
negative numbers.

This was done because of issue1471 but I'm not able to reproduce -that- problem
in the first place on Linux 32bit or 64bit or OS X 10.4 & 10.5 32bit or 64 bit.