build world

Either your computer's date is set incorrectly, or some
/usr/src files have modification date/time set to the
future, but usually the first. This fools make(1) to
think that it should rebuilt sources when it's not supposed
to.

In this case, even though make(1) has already built the
""make_keys"" build-tool for libncurses, it still tries
to rebuild it in the ""library"" stage, when it's not
supposed to.