Add missing Android.mk
Add missing Android.mk

make Triangle was failing due to a missing makefile.  Android build
assumes there will be an Android.mk at each sublevel in the directory
hierarchy when using 'include $(call all-subdir-makefiles)' and will
stop parsing when it hits a directory without a makefile.  Need to
add another Android.mk to ensure Triangle and SpriteText are valid
make targets

Issue: AXIA-2989
Change-Id: Iba6af6e3b3aeb995b7802c3d5264e739e75335f3

android-ia/platform_packages_apps_apps-for-android,android-ia/platform_packages_apps_apps-for-android