I think the legal situation is this:
Converting to SVG is a on-trivial task, and therefore doing it earns you
copyrights.
But the original copyrights continue to apply, as the eventual images look
the same.
What is needed for inclusion in XBoard is that you transfer the
"translation copyrights"
to the FSF, which will then put them under the GPL. But people still won't
still be able
to use the graphics,even when they comply with the GPL, without permission
of the
owner of the copyrights holder for the original pieces. GNU has permission
to use and
distribute these with XBoard, however. (As should be obvious from the fact
we already
use them in pixmap form.)
