gnome-http on HPUX build bugs

[Dan Newcombe <Newcombe mordor clayton edu>]

http_trans.h needs _XOPEN_SOURCE_EXTENDED defined around all the includes.

#ifndef _XOPEN_SOURCE_EXTENDED
#       define _XOPEN_SOURCE_EXTENDED
#endif
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#ifdef _XOPEN_SOURCE_EXTENDED
#       undef _XOPEN_SOURCE_EXTENDED
#endif