The libcanberra port was not in a good state… :)
@tcberner initially wanted to depend on libcanberra-pulse in KDE Plasma 5.
I want to get rid of gtk2 dependencies as much as possible, and libcanberra-gtk was forcing gtk2 onto a lot of systems unnecessarily.
With this update,
- `libcanberra-gtk2` and `libcanberra-gtk3` integrations are in separate packages
- `libcanberra-gtk2` is only depended on when actually used in the port
- header and vapi for gtk (which is used by any of the gtk 2/3) are in the main package, so there's no "require 2 if using 3" or vice versa situation
- well "require 3 if using 2" would kinda be acceptable, but that would be harder to do with the `Uses/canberra.mk` code
- `libcanberra-pulse` and `libcanberra-gstreamer` backends are in separate packages
- `libcanberra-pulse` actually will be used if installed
- the dependency on canberra is written with `USES`
- the canberra dependency is dropped from up-to-date gnome ports (e.g. some games) that have switched to only using the gsound API