build static ssocks by cmake

Add cmake file, build ssocks more easy.

how to build?

windows:

git clone ...
cd ssocks
mkdir build
cd build
cmake ../
cmake --build . --config release

linux:

git clone ...
cd ssocks
mkdir build
cd build
cmake ../
make

cross build:

git clone ...
cd ssocks
mkdir build
cd build
cmake ../ -DCMAKE_C_COMPILER=arm-linux-musleabi-gcc
make

default build static execute

original verison https://github.com/tostercx/ssocks