Added comments for setitimes not supported in vxworks

Author: B I Mohammed Abbas

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

@@ -1337,6 +1337,7 @@ impl File {
                 // Redox doesn't appear to support `UTIME_OMIT`.
                 // ESP-IDF and HorizonOS do not support `futimens` at all and the behavior for those OS is therefore
                 // the same as for Redox.
+                // `futimens` and `UTIME_OMIT` are a work in progress for vxworks. 
                 let _ = times;
                 Err(io::const_io_error!(
                     io::ErrorKind::Unsupported,