close
Same as the standard UNIX routine iconv_close(), but may be implemented via libiconv on UNIX flavors that lack a native implementation. Should be called to clean up the conversion descriptor from g_iconv_open() when you are done converting things.
GLib provides g_convert() and g_locale_to_utf8() which are likely more convenient than the raw iconv wrappers.
Return
-1 on error, 0 on success