localize_hidden: add doc for MacOSX

src/main.rs

@@ -66,6 +66,13 @@ fn link_partial(inputs: Vec<PathBuf>, output: &PathBuf)
 
 fn localize_hidden(input: &PathBuf)
 {
+    /* On MacOSX, check
+     * -[un|re]exported_symbols_list
+     * -[un]exported_symbol
+     * See
+     * https://developer.apple.com/library/archive/technotes/tn2185/_index.html#//apple_ref/doc/uid/DTS10004200-CH1-SUBSECTION5
+     * */
+
     Command::new("objcopy")
         .arg("--localize-hidden")
         .arg("--strip-unneeded")