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: src/common/mgmt/pint-worker-external.po:(.data.rel.local+0x0): multiple definition of
`PINT_worker_external_impl'; src/common/mgmt/pint-mgmt.po:(.bss+0x20): first defined here
