build: New Android makefiles

These form the basis of the new Android build system.

v2: As suggested by Daniel Vetter, modify compilation flags to
not error on return-type and not warn on sign-compare.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
3 files changed