Use lexical-binding in of all lisp/language

* lisp/international/titdic-cnv.el (pinyin-convert):
Enable lexical-binding in the generated file(s).

* lisp/language/ethio-util.el: Use lexical-binding.
(ethio-tex-to-fidel-buffer): Use `inhibit-read-only`.  Remove unused
vars `p` and `ch`.

* lisp/language/hanja-util.el: Use lexical-binding.

* lisp/language/ind-util.el: Use lexical-binding.
(indian-translate-region): Actually use the `from` and `to` arguments.
(<toplevel>): Use `dlet`.  Remove unused var `current-repertory`.
(indian-2-column-to-ucs-region): Remove unused var `pos`.

* lisp/language/japan-util.el: Use lexical-binding.
(japanese-katakana-region, japanese-hiragana-region)
(japanese-zenkaku-region): Remove unused var `next`.

* lisp/language/korea-util.el: Use lexical-binding.

* lisp/language/lao-util.el: Use lexical-binding.
(lao-composition-function): Remove unused var `glyph`.

* lisp/language/thai-util.el: Use lexical-binding.
(thai-composition-function): Remove unused var `glyph`.

* lisp/language/thai-word.el: Use lexical-binding.
(thai-forward-word): Remove unused var `tail`.

* lisp/language/tibet-util.el: Use lexical-binding.
(tibetan-add-components): Remove unused var `tmp`.
(tibetan-compose-region): Remove unused vars `str`, `result`, `chars`.

* lisp/language/viet-util.el:
* lisp/language/tv-util.el:
* lisp/language/cyril-util.el:
* lisp/language/china-util.el: Use lexical-binding.

lisp/language/sinhala.el

@@ -43,6 +43,6 @@
 	 "[\u0D85-\u0D96][\u0D82-\u0D83]?\\|"
 	 ;; any other singleton characters
 	 "[\u0D80-\u0DFF]")
-	0 'font-shape-gstring)))
+	0 #'font-shape-gstring)))
 
 ;; sinhala.el ends here