iBasso DX50/DX90: Rockbox loader, replacement for original firmware MangoPlayer.

This loader is needed to use Rockbox on iBasso DX50/DX90 devices. It replaces
/system/bin/MangoPlayer.

It expects
- the original firmware MangoPlayer as /system/bin/MangoPlayer_original
- the chooser.bmp file as /system/chooser.bmp
- the rbmissing.bmp file as /system/rbmissing.bmp
- the usb.bmp file as  /system/usb.bmp
- Rockbox in /mnt/sdcard/.rockbox/ (internal device storage accessable via USB)

On first boot or if the device is booted with the hold switch engaged (upper,
locked position) this loader will let the user choose between Rockbox and the
orginal firmware MangoPlayer. It remembers the last choice and will start the
choosen player an following boots.

In the chooser screen
- the device can be powered off with a power button long press.
- Rockbox can be startet with the "Next/Fast Forward" button or by touching the
right part of the touchscreen.
- the orginal firmware MangoPlayer can be startet with the "Previous/Rewind"
button or by touching the left part of the touchscreen.

If Rockbox can not be found/executed than a "Rockbox is missing" screen will be
shown and the orginal firmware MangoPlayer will be started after 30 seconds.

This loader will (try to) restart Rockbox or the orginal firmware MangoPlayer if
something unexpected happens.

This loader can be installed via a customized firmware image (update.img) or
manually via the Android Debug Bridge (if you get adbd started on the device).

This is a rewrite and code clean up of the original submission, eliminating the
need for a custom Android Vold. This loader "knows", when Rockbox has exited due
to a USB mass storage connection remounting /mnt/sdcard and acts accordingly,
displaying a "USB connection" screen while waiting to restart Rockbox.

Change-Id: I2698e173437f9c7aa1ff40649a290220e2ee0439

rbutil/ibassoboot/jni/Android.mk

@@ -3,4 +3,12 @@ include $(CLEAR_VARS)
 
 LOCAL_MODULE    := MangoPlayer
 LOCAL_SRC_FILES := ibassodualboot.c qdbmp.c
+
+TARGET_ARCH=arm
+TARGET_PLATFORM=android-14
+TARGET_ARCH_ABI=armeabi
+
+#LOCAL_CFLAGS := -DDEBUG
+#LOCAL_LDLIBS := -llog
+
 include $(BUILD_EXECUTABLE)