Move check from TClass::GetClass to TCling::CheckClassInfo

with the advantage of not calling TEnum::GetEnum for fundamental
types.
Indeed it is now after the check
   THashTable *typeTable = dynamic_cast<THashTable*>( gROOT->GetListOfTypes() );
   TDataType *fundType = (TDataType *)typeTable->THashTable::FindObject( name );
Avoid recursive call to TClass during the creation of TClass instances