video/out: remove options argument from preinit()

All VOs use proper option parsing now, and compatibility hacks are not
needed.
audio/out: remove options argument from init()

Same as with VOs in the previous commit.
options: make legacy hacks for AFs/VFs more explicit

This means that AOs/VOs with no options set do not take the legacy
option parsing path, but instead report that they have no options.