[kernel] Get rid of obsolete thread loading state

The thread::state::loading flag was left over from a time when the
kernel did elf loading for all processes.

src/kernel/syscalls/thread.cpp

@@ -19,7 +19,6 @@ thread_create(j6_handle_t *self, process *proc, uintptr_t stack_top, uintptr_t e
     thread *child = proc->create_thread(stack_top);
     child->add_thunk_user(entrypoint);
     *self = child->self_handle();
-    child->clear_state(thread::state::loading);
     child->set_state(thread::state::ready);
 
     log::debug(logs::task, "Thread %llx:%llx spawned new thread %llx:%llx",