Jack: change free to jack_free
Jack: change free to jack_free

Reported by Graham Goode. Fixes crashes on the Windows platform.

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