audio/lmms: Fix build with FluidSynth 2.x

plugins/sf2_player/sf2_player.cpp:101:20: error: use of undeclared identifier 'FLUID_REVERB_DEFAULT_ROOMSIZE'

m_reverbRoomSize( FLUID_REVERB_DEFAULT_ROOMSIZE, 0, 1.0, 0.01f, this, tr( "Reverb Roomsize" ) ),
                  ^

plugins/sf2_player/sf2_player.cpp:102:19: error: use of undeclared identifier 'FLUID_REVERB_DEFAULT_DAMP'; did you mean 'FLUID_INTERP_DEFAULT'?

m_reverbDamping( FLUID_REVERB_DEFAULT_DAMP, 0, 1.0, 0.01, this, tr( "Reverb Damping" ) ),
                 ^~~~~~~~~~~~~~~~~~~~~~~~~
                 FLUID_INTERP_DEFAULT

[...]
plugins/sf2_player/sf2_player.cpp:395:17: error: variable has incomplete type 'fluid_preset_t' (aka '_fluid_preset_t')

fluid_preset_t preset;
               ^

/usr/local/include/fluidsynth/types.h:41:16: note: forward declaration of '_fluid_preset_t'
typedef struct _fluid_preset_t fluid_preset_t; /**< SoundFont preset */

^

PR: 233462
Approved by: rodrigo (maintainer timeout, 2 weeks)
Obtained from: upstream