I've often found that trying to compile decade-old C code with a current toolchain and current libraries will have issues. It isn't always clear what versions the code is expecting (no equivalent to a lockfile), newer C compilers or standards can break old code, and newer libraries especially can break old code. It might still build if you could recreate exactly what it expects, but it becomes decreasingly possible to do that if you weren't compiling it a decade ago and archived off exactly what worked then.