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: listindex.o:/build/btar-1.1.1/loadindex.h:12: multiple definition of
`ptr'; main.o:/build/btar-1.1.1/loadindex.h:12: first defined here
The patch from OpenSUSE fixes the build with a more recent librsync.
I haven't tested that it runs, but the patch is very simple, and if it
works for OpenSUSE, it should work for us too.
