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
as discussed in the thread starting at
https://sourceware.org/ml/libc-alpha/2015-06/msg00098.html
it looks like the best options is to remove locale timezone information
from locales which currently provide it (in incomplete or incorrect
fashion) rather than to start duplicating tzdata info in glibc.
