Are you using C or C++? Your includes are for C headers (with a C++ header commented out). In your makefile, you're using KOS_CC, which should be a C compiler (vs. KOS_CXX), but you're linking with the C++ standard library (-lstdc++). If you're using C++ you might want to try std::snprintf instead (or put using namespace std; after your includes). The compiler is passing the preprocessor stage since you're getting semantic analysis errors, so your include statements are working. It's not a linker error, although I suspect your linking isn't all there. Other than that, it's hard to say. You could see if snprintf's declaration is being preprocessed out with #ifndef/#ifdef/#if directives in stdio.h.
c++.
I feel like neo when he took the pill..(going from ms vs to vim and having to setup everything)
changed the makefile to kos_cpplus, still complaining, tried both the default cstdio and the one in global, same thing.
and then....... in environ from export KOS_CPPFLAGS="-std=c++11" to export KOS_CPPFLAGS="-std=gnu++11", and my life is complete.