Other modules that depends on it, can reuse includes on linking.
There some files formally not belonging any packages (lib directory), as workaround there temporary include_directories(cfile) on root of project. After migrating all modules this can be removed.
Linux-specific byteswap.h just includes BYTESWAP.H, so there no need platform-specific header.
Fixes "non-portable path to file" ([-Wnonportable-include-path]) warnings.