Fix FluidSynth mode and polyphony

prboom2/src/MUSIC/flplayer.c

@@ -166,9 +166,9 @@ static int fl_init (int samplerate)
   // gain control
   FSET (num, "synth.gain", mus_fluidsynth_gain / 100.0); // 0.0 - 0.2 - 10.0
   // behavior wrt bank select messages
-  FSET (str, "synth.midi-bank-select", "gm"); // general midi mode
-  // general midi spec says no more than 24 voices needed
-  FSET (int, "synth.polyphony", 24);
+  FSET (str, "synth.midi-bank-select", "gs"); // fluidsynth default
+  // general midi spec says 24 voices, but modern midi songs use more
+  FSET (int, "synth.polyphony", 256); // fluidsynth default
 
   // we're not using the builtin shell or builtin midiplayer,
   // and our own access to the synth is protected by mutex in i_sound.c