unix fs: Make hurd using explicit new rather than From

408c0ea ("unix time module now return result") dropped the From
impl for SystemTime, breaking the hurd build (and probably the horizon
build)

Fixes #123032

Author: sthibaul

library/std/src/sys/pal/unix/fs.rs

@@ -515,11 +515,16 @@ impl FileAttr {
         SystemTime::new(self.stat.st_mtime as i64, 0)
     }
 
-    #[cfg(any(target_os = "horizon", target_os = "hurd"))]
+    #[cfg(target_os = "horizon")]
     pub fn modified(&self) -> io::Result<SystemTime> {
         Ok(SystemTime::from(self.stat.st_mtim))
     }
 
+    #[cfg(target_os = "hurd")]
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        SystemTime::new(self.stat.st_mtim.tv_sec as i64, self.stat.st_mtim.tv_nsec as i64)
+    }
+
     #[cfg(not(any(
         target_os = "vxworks",
         target_os = "espidf",
@@ -543,11 +548,16 @@ impl FileAttr {
         SystemTime::new(self.stat.st_atime as i64, 0)
     }
 
-    #[cfg(any(target_os = "horizon", target_os = "hurd"))]
+    #[cfg(target_os = "horizon")]
     pub fn accessed(&self) -> io::Result<SystemTime> {
         Ok(SystemTime::from(self.stat.st_atim))
     }
 
+    #[cfg(target_os = "hurd")]
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        SystemTime::new(self.stat.st_atim.tv_sec as i64, self.stat.st_atim.tv_nsec as i64)
+    }
+
     #[cfg(any(
         target_os = "freebsd",
         target_os = "openbsd",