As of Git Hash: 4a004ad, we have added several checks on C++ compiler on your system so that the transition to C++ phase go smoothly.
What does this mean to you?
You have to install g++ on your system if you don't have it installed on your system.
To do so, you can run the following command
CentOS
sudo yum install gcc-c++
Debian/Ubuntu
sudo apt-get install g++
For OSX you can use your clang/llvm toolchain to compile rAthena.
After that, make sure you have G