Re: arm-none-eabi-toolchain: stdlib.h not found

[Rutherther]

Hello Ekaitz,

the issue here is that the CROSS_CPLUS_INCLUDE_PATH contains
the C include path first, but cstdlib is using #include_next "stdlib.h".
Since stdlib.h is previous to cstdlib in include paths, stdlib.h is not
found as "next". As a workaround, change the order in this variable.

Another issue you might have is the libstdc++ not being linked properly,
that might be because currently it outputs to /lib inside of package
output instead of arm-none-eabi/lib. You might try adding the 
$GUIX_ENVIRONMENT/lib
into your CROSS_LIBRARY_PATH as a workaround.

Regards,
Rutherther