This patch normalizes what the tests do before exiting. After this
change each test should call final on the top module and explicitly
free the top module object before exiting.
cint.mainInt(nodep) walks the tree and populates m_ctorVarsVec.
Reuse EmitCImp cint for the slow mainImp() emition steps to make sure
we emit constructor calls to setup SystemC sc_module names.