[iso] fix UDF UNICODE support

* libcdio's unicode16_decode() was not decoding labels at all,
  but simply stripping the MSB of the UDF USC-16 sequences
* use an actual conversion to UTF-8
* also update the rest of udf_fs.c to latest libcdio version
* closes #285

src/libcdio/driver/utf8.c

@@ -113,7 +113,6 @@ FILE* fopen_utf8(const char* filename, const char* mode)
 }
 #endif
 
-#ifdef HAVE_JOLIET
 #ifdef HAVE_ICONV
 #include <iconv.h>
 struct cdio_charset_coverter_s
@@ -344,5 +343,3 @@ bool cdio_charset_to_utf8(const char *src, size_t src_len, cdio_utf8_t **dst,
   return (*dst != NULL);
 }
 #endif /* HAVE_ICONV */
-
-#endif /* HAVE_JOLIET */