Use lexical-binding in several language support libraries

Use lexical-binding in several language support libraries

* lisp/language/burmese.el:
* lisp/language/cham.el:
* lisp/language/czech.el:
* lisp/language/georgian.el:
* lisp/language/greek.el:
* lisp/language/khmer.el:
* lisp/language/romanian.el:
* lisp/language/sinhala.el:
* lisp/language/slovak.el:
* lisp/language/tai-viet.el:
* lisp/language/vietnamese.el: Use lexical-binding.