smb_mbc_vdecodef
rc = smb_mbc_vdecodef(&sr->smb_vwv, fmt, ap);
rc = smb_mbc_vdecodef(&sr->smb_data, fmt, ap);
xx = smb_mbc_vdecodef(mbc, fmt, ap);
xx = smb_mbc_vdecodef(&tmp, fmt, ap);
int smb_mbc_vdecodef(mbuf_chain_t *, const char *, va_list);