fix macOS build (following Projucer changes made in Windows, which removed /Applications/JUCE/modules from its headers). move JUCE headers under source control, so that Windows and macOS can both build against same version of JUCE. remove AUv3 target (I think it's an iOS thing, so it will never work with this macOS fluidsynth dylib).

modules/juce_core/native/java/AndroidMidiFallback.java

@@ -0,0 +1,85 @@
+    //==============================================================================
+    public class BluetoothManager
+    {
+        BluetoothManager()
+        {
+        }
+
+        public String[] getMidiBluetoothAddresses()
+        {
+            String[] bluetoothAddresses = new String[0];
+            return bluetoothAddresses;
+        }
+
+        public String getHumanReadableStringForBluetoothAddress (String address)
+        {
+            return address;
+        }
+
+        public int getBluetoothDeviceStatus (String address)
+        {
+            return 0;
+        }
+
+        public void startStopScan (boolean shouldStart)
+        {
+        }
+
+        public boolean pairBluetoothMidiDevice(String address)
+        {
+            return false;
+        }
+
+        public void unpairBluetoothMidiDevice (String address)
+        {
+        }
+    }
+
+    //==============================================================================
+    public class MidiDeviceManager
+    {
+        public MidiDeviceManager()
+        {
+        }
+
+        public String[] getJuceAndroidMidiInputDevices()
+        {
+            return new String[0];
+        }
+
+        public String[] getJuceAndroidMidiOutputDevices()
+        {
+            return new String[0];
+        }
+
+        public JuceMidiPort openMidiInputPortWithJuceIndex (int index, long host)
+        {
+            return null;
+        }
+
+        public JuceMidiPort openMidiOutputPortWithJuceIndex (int index)
+        {
+            return null;
+        }
+
+        public String getInputPortNameForJuceIndex (int index)
+        {
+            return "";
+        }
+
+        public String getOutputPortNameForJuceIndex (int index)
+        {
+            return "";
+        }
+    }
+
+
+    public MidiDeviceManager getAndroidMidiDeviceManager()
+    {
+        return null;
+    }
+
+    public BluetoothManager getAndroidBluetoothManager()
+    {
+        return null;
+    }