also perform abstraction computations in feasibility checks, and consequently, during edge interpolation;
this is needed in case ValueCPA has a blacklist or does not track some types of variables which are in turn tracked by, e.g., the BddCPA;
without this change, a path was declared as infeasible, despite the reason of infeasibility was due to variables outside the precision;
the same is true for interpolation, where without this change, variables ended up in the interpolant, despite being excluded in the main analysis, so the interpolant/precision increment was ineffective

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@14659 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c