Merge branch 'fchownat-uid-gid-negative-1' into 'master'

fchownat: fix behavior for uid == -1 && gid == -1

See merge request redox-os/relibc!1243

src/platform/redox/mod.rs

@@ -333,11 +333,7 @@ impl Pal for Sys {
         }
         let path = path.to_str().map_err(|_| Errno(EINVAL))?;
         let file = openat2(fildes, path, flags, 0)?;
-        libredox::fchown(
-            *file as usize,
-            owner.try_into().map_err(|_| Errno(EINVAL))?,
-            group.try_into().map_err(|_| Errno(EINVAL))?,
-        )?;
+        libredox::fchown(*file as usize, owner as _, group as _)?;
         Ok(())
     }