[RFC] remove c++ stuff from clint.py

This WIP removes lots of C++ only checks from clint.py. This still needs some cleanup but the speed improvement are already impressive:

Old:

    /usr/bin/time -p sh -c '../clint.py eval.c > /dev/null 2>&1; true'      
    real 45.39
    user 45.09
    sys 0.01

New:

    /usr/bin/time -p sh -c '../clint.py eval.c > /dev/null 2>&1; true'
    real 4.65
    user 4.61
    sys 0.01

There might be a regression in the struct linting because I removed that together with some of the class linting stuff. I've tested for regressions with the current code but didn't find any.