message: Don't try to encode utf-8 to utf-8
diff: #define ICONV_CONST const
  #endif
  +static std::string filterUtf8Compatible(std::string enc) {
  +#ifdef LCF_SUPPORT_ICU
  + if (ucnv_compareNames(enc.c_str(), "UTF-8") == 0) {
  + return "";
  + }
  +#endif
  + return enc;
  +}
  +
  Encoder::Encoder(std::string encoding)
  - : _encoding(std::move(encoding))
  + : _encoding(filterUtf8Compatible(std::move(encoding)))
  {
  Init();
  }
  