pthread.h fallout with _XOPEN_SOURCE

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Compiling a program like:

#define _XOPEN_SOURCE 500
#include <pthread.h>

Now fails like this:

In file included from /usr/include/pthread.h:46,
                 from test.c:2:
/usr/include/sys/pset.h:46: error: expected '=', ',', ';', 'asm' or
'__attribute__' before 'processorid_t' /usr/include/sys/pset.h:49:
error: expected declaration specifiers or '...' before 'cpuid_t'