Fix lang matching logic

Previous code was broken logically, but harmless.

src/hb-ot-tag.cc

diff --git a/src/hb-ot-tag.cc b/src/hb-ot-tag.cc
index 5dd005f..07ae310 100644
--- a/src/hb-ot-tag.cc
+++ b/src/hb-ot-tag.cc
@@ -845,7 +845,7 @@
     {
       const LangTagLong *lang_tag;
       lang_tag = &ot_languages_zh[i];
-      if (lang_matches (lang_tag->language, lang_str))
+      if (lang_matches (lang_str, lang_tag->language))
 	return lang_tag->tag;
     }