Increase intermediate buffers for wrbuf+iconv.
Increase intermediate buffers for wrbuf+iconv.

The intermediate buffer for wrbuf+iconv is increased from 12 to 16
bytes. There may be MARC-8 sequence overflows overwise - with at
least reset (flush).

nla/yaz,nla/yaz,dcrossleyau/yaz,dcrossleyau/yaz,nla/yaz,nla/yaz,dcrossleyau/yaz