Cover the srv_suspend_thread() call by the kernel mutex. This change was

forgotten when I reverted the kernel mutex split patch.

storage/innobase/srv/srv0srv.c

@@ -3078,9 +3078,13 @@ srv_purge_thread(
 		srv_sync_log_buffer_in_background();
 	}
 
+	mutex_enter(&kernel_mutex);
+
 	/* Decrement the active count. */
 	srv_suspend_thread();
 
+	mutex_exit(&kernel_mutex);
+
 	/* Free the thread local memory. */
 	thr_local_free(os_thread_get_curr_id());