I didn't remember firstchess to have these issues at compiling.

Maybe you can give a try to secondchess. It was my own project some years ago, and it's basically firstchess + castle + ep. So the code isn't much more complex than first chess:
https://github.com/emdio/secondchess

BTW in the repo ...

If you find TSCP hard to understand maybe you can try Firstchess:
http://chessprogramming.wikispaces.com/Firstchess

Take into account that Firschess lacks en pasant capture and castle, but you can get a proper idea of how a chess engine works.

If Firstchess is still to difficult for you, then ...