configure error in HP-UX 11.00

When trying to build the CVS source on a HP-UX 11.00 box:
HP-UX hpux B.11.00 A 9000/800
We got the configure error:

<error>
checking types of arguments for accept()... configure: error: could not 
determine argument types
</error>

Check the config.log, it said that the configure script can't find the 
argument types
fo 'accept()'. but in /usr/include/sys/socket.h, there is prototype of 
accept:

<codesnip>
#if defined(_XOPEN_SOURCE_EXTENDED) && !defined(_KERNEL_BUILD)  extern int accept __((int, struct sockaddr *, socklen_t
*));
...
#else  /* !_XOPEN_SOURCE_EXTENDED*/  extern int accept __((int, void *, int *));
</codesnip>

so what's wrong with the OS?

Thank you

Laser