apply FLUID_DEPRECATED for public synth functions
apply FLUID_DEPRECATED for public synth functions

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