[racket] build-struct-generation

That fix worked -- thanks!

Yep, it did have a "mzscheme" whiff about it.

It would be good for b-s-g to cross-reference d-s/d (I see a
define-struct/derived, not struct/derived) -- I wouldn't have found it
from the docs alone.

However, I am a little unclear on the value of d-s/d.  Is it solely to
improve error messages?  For all other intents, is it equivalent to
writing define-struct without that first syntax object argument?
Perhaps a additional sentence in the docs to either confirm this or
explain the difference would help.

Shriram