ok guenther millert kettenis

changes to libevent and zlib headers sent to the upstream maintainers.
ok jmc@ (for typos), millert@

(not really useful for now, it mostly helps some programs which want
to use it, it will become useful when we have full 16 bits locale).

entire trees for testing anyway, I might as well do this intrusive touching
of include files now.  Added openBSD tags.