dfu-util: missing includes

[Werner Almesberger]

Bruce Cran wrote:
> include unistd.h and stdlib.h: src/main.c needs stdlib.h and unistd.h
> while src/sam7dfu.c just needs unistd.h - they should ideally be
> explicitly included instead of picking them up from libusb.

I've added them to http://svn.openmoko.org/trunk/src/host/dfu-util/
SVN revision 4917,

Thanks !

- Werner