Fix null pointer exception in ladspa

[xobs]

This patchset performs a number of improvements:

1. It uses a locally-patched version of ladspa.rs, at least until the fixes get upstreamed. This is to work around a new issue where pipewire appears to call the initialization functions with null pointers. This also uses a newer version of bitvlags internally.
2. It removes an unsound global static variable that was sharing Rc<T> structs between threads
3. It runs cargo fmt on the repository, which hifts some things around

With this, I'm able to run the example locally without it crashing on Fedora 42, though there are several error messages from within ladspa.rs about being called with a NULL instance.

This closes #644