AllocatedPipe::close(): use Drop & use self

[anemoneflower]

rv6/kernel-rs/src/pipe.rs

Lines 160 to 168 in 5bbd4f0

	// TODO: use `Drop` instead of `close`
	// TODO: use `self` instead of `&mut self`
	// `&mut self` is used because `Drop` of `File` uses AllocatedPipe inside File.
	// https://github.com/kaist-cp/rv6/pull/211#discussion_r491671723
	pub unsafe fn close(&mut self, writable: bool) {
	if (*self.ptr).close(writable) {
	kernel().free(Page::from_usize(self.ptr as *mut Pipe as _));
	}
	}