SupportLeanbackShowcase: add Android.mk am: de41d1a459 am: 958d13b223
am: bf45b9a338

* commit 'bf45b9a338b1eb26611f417fad15289dff48e348':
  SupportLeanbackShowcase: add Android.mk

Change-Id: If870dc6a27a88f898f0327d0ec1093589d7a8ce5