Update Android build to build without the deprecated standalone tools

[WAvdBeek]

Update Android build to build without the deprecated standalone tools Currently the Android build uses the standalone tool chain when the standalone tool chain is installed a warning is printed stating that the standalone tool chain is no longer necessary.

./android-sdk-linux/ndk-bundle/build/tools/make_standalone_toolchain.py --arch arm --api 23 --install-dir ~/android-arm-23 WARNING:main:make_standalone_toolchain.py is no longer necessary. The $NDK/toolchains/llvm/prebuilt/linux-x86_64/bin directory contains target-specific scripts that perform the same task. For example, instead of:

$ python $NDK/build/tools/make_standalone_toolchain.py \
    --arch arm --api 23 --install-dir toolchain
$ toolchain/bin/clang++ src.cpp

Instead use:

$ $NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi23-clang++ src.cpp

We do not know how long the standalone tool chain will continue to be supported by Google so we should update the make files to move away from from the standalone tool chain.