mkdir: permissions respects umask

- hardcoded default permissions changed to ones defined by umask

src/uu/mkdir/src/mkdir.rs

@@ -64,7 +64,10 @@ fn get_mode(matches: &ArgMatches, mode_had_minus_prefix: bool) -> Result<u32, St
             }
             Ok(new_mode)
         }
-        None => Ok(DEFAULT_PERM),
+        None => {
+            // If no mode argument is specified return the mode from umask
+            Ok(mode::get_umask())
+        }
     }
 }
 
@@ -119,7 +122,7 @@ pub fn uu_app<'a>() -> App<'a> {
                 .short('m')
                 .long(options::MODE)
                 .help("set file mode (not implemented on windows)")
-                .default_value("755"),
+                .takes_value(true),
         )
         .arg(
             Arg::new(options::PARENTS)