Add optimization for linux: Reopen pipe as fifo

so that we could set `O_NONBLOCK` on it.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

src/unix.rs

@@ -155,6 +155,14 @@ impl Client {
             (read_err, write_err) => {
                 read_err?;
                 write_err?;
+
+                #[cfg(target_os = "linux")]
+                // Optimization: Try converting it to a fifo by using /dev/fd
+                if let Ok(Some(jobserver)) =
+                    Self::from_fifo(&format!("/dev/fd/{}", read.as_raw_fd()))
+                {
+                    return Ok(Some(jobserver));
+                }
             }
         }