[PATCH] [gold] Implement HIDDEN syntax in linker scripts

[Cary Coutant]

> gold/
> 2016-08-06  Roland McGrath  <roland@hack.frob.com>
>
>       * yyscript.y (HIDDEN): New %token.
>       (assignment): Handle HIDDEN(string = expr) syntax.
>       * script.cc (script_keyword_parsecodes): Add HIDDEN.

This is OK. Thanks!

-cary