Optimization: More direct re-formulation of Python3 base class check.
Optimization: More direct re-formulation of Python3 base class check.

* Checking the truth value of the "tmp_bases" which is of known
  length made no sense to be done in the node tree, we can do this
  at the time of tree building.

* Less noise during optimization at the prize of more branches in
  real compiler code.

kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka