SCons: Only pass CCFLAGS to compilers that accept them

Created by: Protofall

Eg -fdiagnostics-color=always is only for GCC and even then, it doesn't work with KOS' GCC 4.7.3 (Probs because it didn't exist then). We should also use CCVERSION to check if the flag exists in that version.

And yeah, change over from CFLAGS to CCFLAGS so it works on both C and C++.

Also CC and CCVERSION are just for C. CXX CXXVERSION are the ones used for just C++.