build opencv (3.0.0) for android form source

# Set up your NDK path. You also need java 6+, ant 1.8+, and python 2.7 according to opencv doc.
unzip ~/Downloads/opencv-3.0.0.zip
cd opencv-3.0.0/platforms
mkdir build_android_arm
cd build_android_arm
cmake -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON -DCMAKE_TOOLCHAIN_FILE=../android/android.toolchain.cmake $@ ../..
# If you prefer clang to gcc
# cmake -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON -DCMAKE_TOOLCHAIN_FILE=../android/android.toolchain.cmake -DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-clang3.6 $@ ../..
make -j 8

make install
# Till now, opencv is build, you will get a bunch of static libs by default. Everything is under build_android_arm/install