Switch wavpack recipe from autotools to cmake

This was disabled in 4bebbb90 to allow windows CI to work correctly (aka not hang during autoreconf) and we were supposed to revisit it, but we never did.

Since then, libdv has been ported to Meson and the plugin is built on Windows again. The dvd plugins are probably not being used at all on Windows, which leaves a52dec and wavpack.

wavpack has cmake build files, so we should see whether we can switch to that instead.

a52dec will need a port to meson, so we need someone to spend a non-trivial amount of time on it. That will have to happen later.

Marking as a blocker for 1.20, but that's just as a reminder for myself. Please feel free to remove it if it actually blocks the release. We can always re-add it later.