`cc` call in setup.py failing for conda-forge build
These compilation checks are causing issues because cc
isn't defined in the docker images that conda-forge uses:
https://gitlab.com/ifosim/finesse/finesse3/-/blob/develop/setup.py#L35
We just need to change this to check the $CC
environment variable and if it exists use that. I've added a conda-forge patch for 3.0a6 for now but that should be removed and fixed for the next release push