We need to add the gcc in the PATH, but adding it directly to $PATH doesn't work, as it will be restored to $path_backup before icc runs. So for now we simply inject it to path_backup, but ideally we should find a more robust solution.
In the future, we may want to look if those symlinks are needed.
The stdenv no longer provides it by default. Reviewed-by: Aleix Boné <abonerib@bsc.es> Tested-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
