neweff prod work: Use update code instead of duplicating it

neweff prod work: Use update code instead of duplicating it

The code to build sectors got quadruplicated in Chainsaw.  We've since
fixed numerous inconsistencies, but still have four copies of the
code.  Thanks to the recent work on upd_buildeff(), we can now use it
to replace the other three copies.  Rename it back to to buildeff()
while there.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>