[patch 6/7] [gold] Add initial source code for dwp utility.

[Cary Coutant]

>> +       * dwp.cc (Dwo_file::remap_str_offset): Use section_offset_type
>> +       on val.
>> +
>
> This is OK if it's OK with Cary.

This is OK with me, too. Thanks!

Sorry for the breakage -- I learned a while ago that I need to do
32-bit builds to look for such things, but forgot this time.

-cary