stty: Use c_line (as line_discipline) from nix

Nix now supports the line discipline parameter in various platforms,
so use upstream definition instead of going through libc

See: nix-rust/nix#1802

Author: 3v1n0

src/uu/stty/src/stty.rs

@@ -658,12 +658,9 @@ fn print_terminal_size(
         );
     }
 
-    #[cfg(any(target_os = "linux", target_os = "redox"))]
+    #[cfg(any(target_os = "linux", target_os = "android", target_os = "haiku"))]
     {
-        // For some reason the normal nix Termios struct does not expose the line,
-        // so we get the underlying libc::termios struct to get that information.
-        let libc_termios: nix::libc::termios = termios.clone().into();
-        let line = libc_termios.c_line;
+        let line = termios.line_discipline;
         printer.print(&translate!("stty-output-line", "line" => line));
     }
     printer.flush();
@@ -1042,7 +1039,7 @@ fn apply_special_setting(
         )]
         SpecialSetting::Line(n) => {
             // nix only defines Termios's `line_discipline` field on these platforms
-            #[cfg(any(target_os = "linux", target_os = "android"))]
+            #[cfg(any(target_os = "linux", target_os = "android", target_os = "haiku"))]
             {
                 _termios.line_discipline = *n;
             }