Add disableCc=True to SConstruct.

[wmwv]

This is a pure-Python package that doesn't need to compile any C++.

[timj]

Would you mind fixing the python/lsst/validate/drp/util.py yaml.load warnings whilst you are here? It might be that a trivial change to use safe_load will fix the warnings.

[wmwv]

I'm going to do the safe_load on a separate ticket because I actually want to test and make sure the safe_load works beyond just making sure the Jenkins run passes. E.g., I'm concerned that changing the yaml loading may change the logic of what validate_drp actually tries to do -- it still might succeed but it might skip half the tests. So I'm going to read the outputs, etc. for such an update.