[gold][patch] a bit of plugin code refactoring

[Cary Coutant]

>> 2009-02-15  Rafael Avila de Espindola  <espindola@google.com>
>>
>>       * archive.cc (Archive::include_member): Update calls to add_symbols.
>>       * dynobj.cc (Sized_dynobj<size, big_endian>::make_version_map): Add
>>       the Layout argument.
>>       * dynobj.h (do_add_symbols): Add the Layout argument.
>>       * object.cc (Sized_relobj<size, big_endian>::do_add_symbols): Add the
>>       Layout argument.
>>       * object.h (Object::add_symbols): Add the Layout argument.
>>       (Object::do_add_symbols): Add the Layout argument.
>>       (Sized_relobj::do_add_symbols): Add the Layout argument.
>>       * plugin.cc (Sized_pluginobj<size, big_endian>::do_add_symbols):
>>       Unify the two versions.
>>       (Add_plugin_symbols): Remove.
>>       * plugin.h (Pluginobj::add_symbols, Pluginobj::do_add_symbols): Remove.
>>       (Sized_pluginobj::do_add_symbols): Unify the two versions.
>>       (Add_plugin_symbols): Remove.
>>       * readsyms.cc (Read_symbols::do_read_symbols): Update call to
>>       Add_symbols. Use Add_symbols instead of Add_plugin_symbols.
>>       (Add_symbols::run): Make it work with Pulginobj.
>
> This is OK.

I've tested and applied it for Rafael.

-cary