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: r_gl.h:52: multiple definition of `qglGenBuffers';
r_gl.h:52: first defined here
Without the change build fails as:
ld: release-linux-x86_64/testall/client/sound/s_mix.c.o: undefined reference to symbol 'acos@@GLIBC_2.2.5'
With change added I was able to start ufoai.
