[tlbuild] missing libiconv when compiling xdvik on FreeBSD

[Karl Berry]

    Does anyone know the best way to proceed?

Does --without-iconv help?

Or, on the other hand:
  --with-iconv-include=DIR  Specify the location of <iconv.h> header
  --with-iconv-libdir=DIR   Specify the location of iconv (-liconv or -lrecode)
                              library

Why configure fails to detect the presence of -liconv would seem to
require dredging through config.log, if there is no answer on the net ... -k