split out sa_family_t to a bits header

src/header/sys_socket/mod.rs

@@ -6,7 +6,7 @@ use core::{mem, ptr};
 
 use crate::{
     error::ResultExt,
-    header::{bits_iovec::iovec, bits_socklen_t::socklen_t},
+    header::{bits_iovec::iovec, bits_safamily_t::sa_family_t, bits_socklen_t::socklen_t},
     platform::{
         PalSocket, Sys,
         types::{
@@ -17,8 +17,6 @@ use crate::{
 
 pub mod constants;
 
-pub type sa_family_t = u16;
-
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/sys_socket.h.html>.
 #[repr(C)]
 #[derive(Default, CheckVsLibcCrate)]