misc: cosmetics, remove argument from usage(FILE*)

misc: cosmetics, remove argument from usage(FILE*)

This patch is trivial and changes nothing, because
we were always using usage(stdout)

Now all our usage() functions look very similar. If wanted we
could auto-generate another big cosmetical patch to remove all
the useless "FILE *out" constants and use printf and puts
rather than their f* friends. Such patch could be automatically
synchronized with the translation project (newlines!) to not
make the translators sick.

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>