implement some stuff to make exaple SDL app run

NOTE: the main addition in this commit is WIP support for apps which
render on an EGL surface obtained using ANativeWindow_fromSurface

currently, this EGL surface is obtained by creating a 700x700 pixel
window with GLFW (the 700x700 size is hardcoded in several places)
and only Wayland is supported

ideally, we'd want to use a wayland subsurface to position the EGL
surface above the Surface widget it's associated with (and do
whatever for X11)

src/api-impl/android/hardware/SensorManager.java

@@ -1,7 +1,13 @@
 package android.hardware;
 
+import android.os.Handler;
+
 public class SensorManager {
     public Sensor getDefaultSensor(int type) {
 		return null;
     }
+
+	public boolean registerListener (SensorEventListener listener, Sensor sensor, int samplingPeriodUs, Handler handler) {
+		return true; // we could try saying that the sensor doesn't exist and hope the app just doesn't use it then, but as long as we never call the handler the app should leave this alone
+	}
 }

src/api-impl/android/hardware/usb/UsbManager.java

@@ -0,0 +1,9 @@
+package android.hardware.usb;
+
+import java.util.HashMap;
+
+public class UsbManager {
+	public HashMap getDeviceList() {
+		return new HashMap();
+	}
+}