ndef: return not implemented for utf16 on ndef text

since noone has discovered how broken this has been since 2012 just
return not yet implemented.

tests/test_ndef_construction.c

@@ -104,17 +104,17 @@ static void _test_other_lang_text(void)
 	YK_NDEF *ndef = ykp_alloc_ndef();
 	char text[] = "aaaaaaaaaaaaaaa";
 	size_t text_len = strlen(text);
-	int rc = ykp_construct_ndef_text(ndef, text, "sv-SE", true);
-	char text2[256];
+	int rc = ykp_construct_ndef_text(ndef, text, "sv-SE", false);
+	char text2[256] = {0};
 	assert(rc == 1);
 	assert(ndef->type == 'T');
-	assert(ndef->data[0] == (0x80 & 5));
+	assert(ndef->data[0] == (5));
 	assert(memcmp(ndef->data + 1, "sv-SE", 5) == 0);
 	assert(memcmp(ndef->data + 6, text, text_len) == 0);
 	assert(ndef->len == text_len + 6);
 	rc = ykp_ndef_as_text(ndef, text2, 256);
 	assert(rc == 1);
-	assert(memcmp(text, text2, strlen(text)));
+	assert(memcmp(text, text2, strlen(text)) == 0);
 	ykp_free_ndef(ndef);
 }
 

ykpers.c

@@ -473,7 +473,8 @@ int ykp_construct_ndef_text(YK_NDEF *ndef, const char *text, const char *lang, b
 	size_t lang_length = strlen(lang);
 	unsigned char status = lang_length;
 	if(isutf16) {
-		status &= 0x80;
+		ykp_errno = YKP_ENOTYETIMPL;
+		return 0;
 	}
 	if((data_length + lang_length + 1) > NDEF_DATA_SIZE) {
 		ykp_errno = YKP_EINVAL;