The CF configure flags broke with the last update but based on
fa9c81f694 and the comment it seems like
these are not necessary anymore.
$ nix-build -A stdenv.__bootPackages.stdenv.__bootPackages.gettext
/nix/store/dii9p8717rjnbzar4kh1q3sxk77dbbkd-gettext-0.20.1
$ nix-store -qR /nix/store/dii9p8717rjnbzar4kh1q3sxk77dbbkd-gettext-0.20.1
/nix/store/2ws9cmamvr7xyvdg4d2nnd1bmr1zjrrq-bootstrap-tools
/nix/store/2yn28axagwyifnvdm8npy2f982jxr986-libiconv-osx-10.12.6
/nix/store/dii9p8717rjnbzar4kh1q3sxk77dbbkd-gettext-0.20.1
27313767b8