Rollup merge of #124649 - Meziu:master, r=ChrisDenton

Fix HorizonOS build broken by #124210

HorizonOS (for the Tier-3 target `armv6k-nintendo-3ds`) does not support `dirfd()`, as many other similar targets.

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

@@ -860,6 +860,7 @@ fn drop(&mut self) {
             target_os = "hurd",
             target_os = "espidf",
             target_os = "fuchsia",
+            target_os = "horizon",
         )))]
         {
             let fd = unsafe { libc::dirfd(self.0) };