tail: avoid unnecessary pipe2 syscall when stdout is already a pipe

Use splice_unbounded_auto instead of splice_unbounded_broker to avoid
creating a broker pipe when stdout is already a pipe (e.g., when piping
to another command with |).

src/uu/tail/src/tail.rs

@@ -596,7 +596,7 @@ fn print_target_section<
         }
     } else {
         #[cfg(any(target_os = "linux", target_os = "android"))]
-        if uucore::pipes::splice_unbounded_broker(file, &mut stdout)?.is_err() {
+        if uucore::pipes::splice_unbounded_auto(file, &mut stdout)? {
             io::copy(file, &mut stdout)?;
         }
         #[cfg(not(any(target_os = "linux", target_os = "android")))]