Make 'thread_id' parameter in os_thread_create() optional.

include/os0thread.h

@@ -77,7 +77,7 @@ os_thread_create(
 	void*			arg,		/* in: argument to start
 						function */
 	os_thread_id_t*		thread_id);	/* out: id of the created
-						thread */
+						thread, or NULL */
 int
 os_thread_join(
 /*===========*/

log/log0recv.c

@@ -2940,7 +2940,6 @@ recv_recovery_from_checkpoint_finish(void)
 /*======================================*/
 {
 	int		i;
-	os_thread_id_t	recovery_thread_id;
 
 	/* Apply the hashed log records to the respective file pages */
 
@@ -2984,7 +2983,7 @@ recv_recovery_from_checkpoint_finish(void)
 		session */
 
 		os_thread_create(trx_rollback_or_clean_all_without_sess,
-				(void *)&i, &recovery_thread_id);
+				(void *)&i, NULL);
 	}
 }
 

os/os0thread.c

@@ -96,7 +96,7 @@ os_thread_create(
 	void*			arg,		/* in: argument to start
 						function */
 	os_thread_id_t*		thread_id)	/* out: id of the created
-						thread */
+						thread, or NULL */
 {
 #ifdef __WIN__
 	os_thread_t	thread;
@@ -122,7 +122,9 @@ os_thread_create(
 		ut_a(SetThreadPriority(thread, srv_query_thread_priority));
 	}
 
-	*thread_id = win_thread_id;
+	if (thread_id) {
+		*thread_id = win_thread_id;
+	}
 
 	return(thread);
 #else
@@ -180,7 +182,9 @@ os_thread_create(
 		my_pthread_setprio(pthread, srv_query_thread_priority);
 	}
 
-	*thread_id = pthread;
+	if (thread_id) {
+		*thread_id = pthread;
+	}
 
 	return(pthread);
 #endif