Add *NSYNC unit test suite

This change also fixes the clock_nanosleep() api and polyfills futexes
on Windows, Mac, and NetBSD using exponential backoff.

libc/thread/freebsd.internal.h

@@ -46,6 +46,7 @@ struct _umtx_time {
 };
 
 int sys_umtx_op(void *, int, unsigned long, void *, void *);
+int sys_umtx_timedwait_uint(int *, int, bool, const struct timespec *);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/thread/pthread_attr_destroy.c

@@ -16,8 +16,8 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/thread/thread.h"
 #include "libc/str/str.h"
+#include "libc/thread/thread.h"
 
 /**
  * Destroys pthread attributes.

libc/thread/pthread_create.c

@@ -182,6 +182,7 @@ static int FixupCustomStackOnOpenbsd(pthread_attr_t *attr) {
  * @raise EINVAL if `attr` was supplied and had unnaceptable data
  * @raise EPERM if scheduling policy was requested and user account
  *     isn't authorized to use it
+ * @returnserrno
  * @threadsafe
  */
 errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,

libc/thread/pthread_detach.c

@@ -29,6 +29,8 @@
  *
  * @return 0 on success, or errno with error
  * @raise EINVAL if thread is null or already detached
+ * @returnserrno
+ * @threadsafe
  */
 int pthread_detach(pthread_t thread) {
   struct PosixThread *pt;

libc/thread/pthread_join.c

@@ -26,6 +26,8 @@
  *
  * @return 0 on success, or errno with error
  * @raise EDEADLK if thread is detached
+ * @returnserrno
+ * @threadsafe
  */
 int pthread_join(pthread_t thread, void **value_ptr) {
   struct PosixThread *pt;

libc/thread/wait0.c

@@ -25,6 +25,7 @@
 #include "libc/errno.h"
 #include "libc/intrin/atomic.h"
 #include "libc/intrin/describeflags.internal.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/nt/runtime.h"
 #include "libc/nt/synchronization.h"
@@ -66,7 +67,7 @@ static void _wait0_futex(const atomic_int *a, int e) {
       rc = -GetLastError();
     }
   } else if (IsFreebsd()) {
-    rc = sys_umtx_op(a, UMTX_OP_WAIT_UINT, 0, 0, 0);
+    rc = sys_umtx_op(a, UMTX_OP_WAIT_UINT, e, 0, 0);
   } else {
     rc = _futex(a, op, e, 0);
     if (IsOpenbsd() && rc > 0) {