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
Workaround build failure on -fno-common toolchains like upstream
gcc-10. Otherwise build fails as:
ld: ./libfml.a(rle.o):/build/source/SeqLib/fermi-lite/rle.h:33: multiple definition of
`rle_auxtab'; ./libfml.a(misc.o):/build/source/SeqLib/fermi-lite/rle.h:33: first defined here