Is there anything I can do to work around it?

  The extra file is "./usr/lib/libgcc_s.a".

Generally you can edit your local sources and modify the file lists.
See src/distrib/sets/lists/comp/mi, for example.

I'm not at all sure where this file belongs, but if you just want to
make a build work I suspect it doesn't matter where you put it.

-- 
        Greg Troxel <gdt@ir.bbn.com>