[HEADSUP] dialog4ports does not popup anymore only for global options

[Vitaly Magerya]

Baptiste Daroussin wrote:
>> So, again, what are my options if I don't want dependencies to be pulled
>> in silently?
> 
> You have no options and you never had one in the ports tree sorry.

Previously maintainers could decide to show dialog with only DOCS or not
to show it.

They didn't do it consistently, of course. Probably because no
guidelines where established.

> If you have a way to implement that cleanly, I'll be happy to push such features
> in the ports but really I see a way to do what you ask for.

We could provide 'OPTIONS_DEFINE_SILENT' for ports that don't want to
spam the users with dialogs, but still want to provide the options. Or a
separate flag, like 'OPTIONS_ARE_SILENT'.