stdenv.targetPlatform really shouldn't be used by software that
doesn't generate or manipulate binaries. I reviewed all uses of
targetPlatform outside of pkgs/development/compilers and pkgs/stdenv
and replaced those which weren't involved in something which fits
these criteria.
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
