[PATCH] gold: remove unused private members

[Cary Coutant]

> gold/
>         * i386.cc (Target_i386): Remove unused member dynbss_.

This appears to be unused in all the other target-specific files as
well. I believe it was replaced by Copy_relocs::dynbss_. While you're
cleaning it up, please remove it from arm.cc, powerpc.cc, sparc.cc,
tilegc.cc, and x86_64.cc.

>         * dwarf_reader.h (Dwarf_info_reader): Remove unused members
>         type_signature_, type_offset_.
>         * plugin.h (Plugin_hook): Remove unused member layout_.
>         * readsyms.h (Add_symbols): Remove unused members dirpath_, dirindex_,
>         mapfile_.
>         (Read_member): Remove unused members input_objects_, symtab_,
>         mapfile_, layout_.
>         (Check_library): Remove unused member symtab_.
>         * archive.h (Lib_group): Remove unused member lib_.
>         * archive.cc (Lib_group::Lib_group): Update initializer.
>         * incremental.h (Incremental_binary): Remove unused member target_.
>         (Incremental_script_entry): Removed unused member script_.
>         * layout.h (Write_symbols_task): Remove unused member input_objects_.
>         * icf.h (Icf): Remove unused member num_tracked_relocs.

This is OK with the changes noted above. Thanks.

-cary