Update for new thread join APIs (#90)

Author: bretambrose

source/s3.c

@@ -126,6 +126,7 @@ void aws_s3_library_clean_up(void) {
     }
 
     s_library_initialized = false;
+    aws_thread_join_all_managed();
 
     aws_hash_table_clean_up(&s_compute_platform_info_table);
     aws_unregister_log_subject_info_list(&s_s3_log_subject_list);

tests/s3_tester.c

@@ -470,12 +470,10 @@ void aws_s3_tester_clean_up(struct aws_s3_tester *tester) {
     aws_event_loop_group_release(tester->el_group);
     tester->el_group = NULL;
 
+    aws_s3_library_clean_up();
+
     aws_condition_variable_clean_up(&tester->signal);
     aws_mutex_clean_up(&tester->synced_data.lock);
-
-    aws_global_thread_creator_shutdown_wait_for(10);
-
-    aws_s3_library_clean_up();
 }
 
 void aws_s3_tester_lock_synced_data(struct aws_s3_tester *tester) {