Add libgcc to conda install to address issue 339
Add libgcc to conda install to address issue 339

Work around version incompatibility between the scipy version in conda
and the system-provided /usr/lib/x86_64-linux-gnu/libstdc++.so.6
by installing a conda-provided libgcc and adding it to the load path

cleverhans-lab/cleverhans,openai/cleverhans,carlini/cleverhans,cihangxie/cleverhans,carlini/cleverhans,cleverhans-lab/cleverhans,cleverhans-lab/cleverhans