Logged In: YES 
user_id=21627

Now we are getting closer. What is the specific line in
sys/socket.h that gives the syntax error? Are there
alternative definitions of the (function, I suppose), either
in socket.h or in another file? Why is u_int not defined
when _XOPEN_SOURCE is?

IOW: Are you absolutely, definitely, 100% certain that there
is no way to compile sys/socket.h when _XOPEN_SOURCE is
defined? That would be a serious bug in the system.

Now, if we can establish with certainty that the system is
broken beyond repair, it is acceptable to work around the
bugs, by not defining _XOPEN_SOURCE. We then need to record
the specific release of the system that we found is broken,
and we need to document what specifically we found broken
about it. For better reproducability, we also want to record
the name of the person who determined the system being broken.

We do all this in the hope that future system releases will
be fixed by the system vendors, and that our work-arounds
won't be needed anymore when we stop supporting old releases
of the system (at a time when nobody uses those old releases
anymore).

I am not opposed to setting _define_xopen_source=no in
principle (I once was, but am not any longer). I only want a
convincing analysis that this is necessary to get essential
parts of Python (such as sockets) to work.