Android build porting(use toolchain).

Standalone Toolchain
====================

Make standalone android ndk toolchain($NDK/docs/STANDALONE-TOOLCHAIN.html):
$cd $NDK_ROOT
$./build/tools/make-standalone-toolchain.sh --platform=android-14 --install-dir=~/toolchains/arm-linux-androideabi-r9d-14
$export PATH=$PATH:~/toolchains/arm-linux-androideabi-r9d-14/bin


Source Install
====================

$cd build
$cmake -D CMAKE_TOOLCHAIN_FILE=../cmake/android.toolchain.cmake -G "Unix Makefiles" ..
$make -j4