with structuredAttrs lists will be bash arrays which cannot be exported
which will be a issue with some patches and some wrappers like cc-wrapper
this makes it clearer that NIX_CFLAGS_COMPILE must be a string as lists
in env cause a eval failure
To keep this for the future we also strictDeps where possible, including for janePackages, topkg, oasis and ocamlbuild.
This makes some closures significantly smaller and makes cross compilation easier