Multi iconv conversions for yaz_opac_decode_wrbuf2
Multi iconv conversions for yaz_opac_decode_wrbuf2

This function uses iconv handle for MARC first; failing that uses iconv
handle supplied to function yaz_opac_decode_wrbuf. Bug #4048.

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