u_short undefined

Hi,

I'm to compile a program that uses the u_short type synonim on my
ubuntu hoary box. 'make' stops with complaining about lacking a
definition for u_short. I've tracked down what the problem is and
found that <features.h> #undefs __USE_BSD which is important for the
definition of u_short in <sys/types.h>. Is it a proper act from
<features.h> to do so? Is this a special feature of ubuntu?

Thanks in advance

Cheers

- Gergely

ps: is _BSD_SOURCE a proper #define for Linux, especially ubuntu?