Add new thread exception (untested)

src/main.rs

@@ -48,6 +48,7 @@ fn main() {
     system.get_thread_manager().get_g_alive().push(Rc::clone(&thread_exec));
 
     let owner1 = Process { num_thread: 0 };
+    let owner1 = Rc::new(RefCell::new(owner1));
     system.get_thread_manager().start_thread(Rc::clone(&thread_exec), owner1, loader.elf_header.entrypoint, ptr, -1);
     
     let to_run = system.get_thread_manager().find_next_to_run().unwrap();