[gold patch] When comparing two symbols, handle the forwarding case

[Cary Coutant]

> 2018-1-10 Sterling Augustine <saugustine@google.com>
> * cref.cc (Cref_inputs::Cref_table_compare::operator): Add conditionals and
> calls to is_forwarder

This is OK, but please s/-1-/-01-/ in the ChangeLog. Thanks!

-cary