build assimp for android on os x

https://www.bountysource.com/issues/44127272-android-ndk-build-fails

http://www.myandroidonline.com/2015/06/09/compile-assimp-open-source-library-for-android/


https://developer.android.com/ndk/guides/standalone_toolchain.html

$NDK/build/tools/make-standalone-toolchain.sh --arch=arm --verbose --toolchain=arm-linux-androideabi-4.8 --platform=android-21 --install-dir=./my-android-toolchain

cmake -DCMAKE_TOOLCHAIN_FILE=$ANDTOOLCHAIN \

      -DANDROID_NDK=$ANDROID_NDK \

      -DASSIMP_ANDROID_JNIIOSYSTEM=ON \

      -DCMAKE_BUILD_TYPE=Release \

      -DANDROID_ABI="armeabi-v7a" \

      -DANDROID_NATIVE_API_LEVEL=android-21 \

      -DANDROID_FORCE_ARM_BUILD=TRUE \

      -DCMAKE_INSTALL_PREFIX=install \

      -DASSIMP_BUILD_TESTS=OFF \

      ./$ASSIMP

cmake --build .