configure script may not check pthread correctly on OpenBSD

I have come into at least 2 times that one project was built well on Linux , while can’t find pthread related definitions on OpenBSD , like this:

......
../../runtime/cilk-internal.h:39:6: error: unknown type name 'pthread_mutex_t'
     pthread_mutex_t posix;
     ^
../../runtime/cilk-internal.h:211:6: error: unknown type name 'pthread_t'
     pthread_t *tid;
     ^
../../runtime/cilk-internal.h:216:6: error: unknown type name 'pthread_cond_t'
     pthread_cond_t  waiting_workers_cond;
     ^
../../runtime/cilk-internal.h:217:6: error: unknown type name 'pthread_cond_t'
     pthread_cond_t  wakeup_first_worker_cond;
     ^
../../runtime/cilk-internal.h:218:6: error: unknown type name 'pthread_cond_t'
     pthread_cond_t  wakeup_other_workers_cond;
     ^
../../runtime/cilk-internal.h:219:6: error: unknown type name 'pthread_mutex_t'
     pthread_mutex_t workers_mutex;
     ^
../../runtime/cilk-internal.h:220:6: error: unknown type name 'pthread_cond_t'
     pthread_cond_t  workers_done_cond;
......

The source code is as following:

......
#if HAVE_PTHREAD
#include <pthread.h>
#endif
......

While the generated config.h doesn’t define HAVE_PTHREAD macro:

/* Define if you have POSIX threads libraries and header files. */
/* #undef HAVE_PTHREAD */

But in fact, the OpenBSD has provided all support of pthread . So please be aware of this issue.