Fix lang_lib/lang_term as per ISO 639-2 [BZ #16973]

lang_lib (which reflects ISO 639-2/B (bibliographic) codes) and
lang_term (which reflects ISO 639-2/T (terminology) codes) should be
identical except for those languages for which ISO 639-2 specifies
separate bibliographic/terminology values.

I used this Library of Congress page as the source:
	http://www.loc.gov/standards/iso639-2/php/code_list.php