Add Android.mk to use btrfs on android device.
There are still outstanding problems and build support is incomplete:
1) phread_cancel was changed to pthread_kill due to android didn't
support that.
2) This module needs lzo library on android/external folder.
3) blkid library doesn't support fully. So have to use -f option to
work.
Signed-off-by: kenneth.kang <kenneth.kang@lge.com>
Signed-off-by: David Sterba <dsterba@suse.com>
