cloudooo: add gcc in LD_LIBRARY_PATH

On debian 8.5 cloudooo refuses to start with:

./parts/libreoffice-bin/program/soffice.bin: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.9' not found (required by ../parts/mesa/lib/libGL.so.1)

some more info:

# dpkg  -S  /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20
libstdc++6:amd64: /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20