Convert to Soong

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

All the code compilation has moved to Soong, but prebuilts remain in the
Android.mk / Android.ltp.mk, since prebuilts are still a WIP in Soong.
So the generator exports both bp and mk pieces (and a substantial
portion of it is identical between the two)..

VTS installation has moved to
test/vts/tools/build/tasks/vts_native_packages.mk, which includes the
generated android/ltp_package_list.mk to find all the LTP packages. This
is more reliable than before, since there was no dependency from the zip
file to any LTP files.

Test: mmma -j external/ltp
Test: m -j ltp
Test: m -j out/host/linux-x86/vts/android-vts.zip
Change-Id: I5be27ac9f0da5e17d0729ef0dc80ce6f54b10ef1
11 files changed