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
libiconv is already defined per-platform. The actual libiconv library
won't be built on platforms like Linux where it doesn't need to be, so
there's no need to maintain a separate platform list here.
Required to build for FreeBSD.
