C11 conformance of casinl-like functions.

[mokhi]

Hi.

I recently saw bunch of PRs opened about C11 lack of conformance in
FreeBSD on Bugzilla, complaining cosinl, acosinl, ... not implemented.

I've searched about these and I found documents about them too[2][3].
Do you think we should implement them? Or standards doesn't have
suggestions on these?

If yes (you think we should implement them), would you suggest simply
`strong aliasing symbols of FUNC_l to FUNC`? or implementing FUNC_l
from scratch?

I've made some patch based on my idea of aliasing symbols, If you
agree I like to work on this and probably can start a review on
phabricator for that.


Thanks and best wishes, Mokhi.
==========================================
[2] https://www.gnu.org/software/gnulib/manual/gnulib.html
[3] http://pubs.opengroup.org/onlinepubs/9699919799/functions/casinhl.html
and many more like this on opengroup.