Convert libandroid and libandroid_runtime to Android.bp

See build/soong/README.md for more information.

Test: m -j checkbuild
Change-Id: Ie3c9c3d3c8c75ade36422d1e8ee0a5fe117e9091
Merged-In: Ie3c9c3d3c8c75ade36422d1e8ee0a5fe117e9091
(cherry picked from commit 3f8fd40f)