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
Without the change -fno-common toolchains like upstream gcc-10
fail to build as:
ld: afpcmd-cmdline_main.o:/build/source/cmdline/cmdline_afp.h:4: multiple definition of
`full_url'; afpcmd-cmdline_afp.o:/build/source/cmdline/cmdline_afp.c:27: first defined here