Ceres Solver for Android Platform

This project is modified based on Ceres V2.0.0master branch(https://github.com/ceres-solver/ceres-solver)
But original version is not supported for all solver methods and you may only use DENSE_QR.
If you want to use some methods(ex.SPARSE_SCHUR) and you will find you can't use them. So, I modified and make sure it is supported for suites-parse and you can use it for all solvers(ex.trust_region_strategy or SPARSE_NORMAL_CHOLESKY and so on)!

What I change

For supported for suite-sparse
Firstly, I add suitesparse libraries(.so) under 3rdParty
Secondly, I modified both CMakeLists.txt under root path and internal/ceres to force compile SuiteSparse module and add suitesparse libraries depended.

Prepare for

You should download NDK(Mine is android r16) and add NDK path to your environment variable.

How to Compile

Follow command below, and you will get libceres.so for Android platform in android_build/lib/
cd android_build
sh make_ceres.sh (you should change ndk path according to your own)
make
and libceres.so will be saved