Correct typo in #ifdef: PY_THREAD_D4, should be PY_PTHREAD_D4.
Reported by Jonathan Giddy.
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 64100f4..995ef51 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -156,7 +156,7 @@
 				 );
 
 	if (success >= 0) {
-#if defined(PY_THREAD_D4) || defined(PY_PTHREAD_D6) || defined(PY_PTHREAD_D7)
+#if defined(PY_PTHREAD_D4) || defined(PY_PTHREAD_D6) || defined(PY_PTHREAD_D7)
 		pthread_detach(&th);
 #elif defined(PY_PTHREAD_STD)
 		pthread_detach(th);