fix unix typedef

Author: Gankra

library/std/src/os/unix/net/addr.rs

@@ -18,7 +18,7 @@ mod libc {
 fn sun_path_offset(addr: &libc::sockaddr_un) -> usize {
     // Work with an actual instance of the type since using a null pointer is UB
     let base = (addr as *const libc::sockaddr_un).addr();
-    let path = (&addr.sun_path as *const i8).addr();
+    let path = (&addr.sun_path as *const libc::c_char).addr();
     path - base
 }