Store ALIST as the definition of language environment LANG-ENV.
ALIST is an alist of KEY and INFO values. See the documentation of
`language-info-alist' for the meanings of KEY and INFO.
Optional arg PARENTS is a list of parent menu names; it specifies
where to put this language environment in the
Describe Language Environment and Set Language Environment menus.
For example, ("European") means to put this language environment
in the European submenu in each of those two menus.