I don't think we want the new symbols gnu_linux and gnu_hurd symbols predefined without __s. It seems pretty ill-advised to predefine any new symbols in the user/application name space (i.e. without leading _). I never saw RMS suggest defining the unadorned names. Am I clueless about what CPP_PREDEFINES does or should all those -Dgnu_foo be -D__gnu_foo__ instead?