Don't add effect control nodes to global node list
Don't add effect control nodes to global node list

As effect control nodes are private to the effect and only ever
accessed via the effect and port name, they don't need to be added
to the global node list and can be cleaned up in the effect
destructor.

FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth,FluidSynth/fluidsynth