Fast and easy testing of GCC on AlphaRTC

[yooneo0124]

• GCC inside AlphaRTC as a compilable branch #96
• Update README with guides for GCC evaluation and docker-free compilations #102

[yooneo0124]

Update:

• Will maintain gcc_baseline for fast and easy testing of GCC
• Easy configuration of RL-based CC or GCC evaluation and update the README #97 will be addressed in the future milestones