unused variables

gcc shows these warning for unused variables:

```cpp
postpuff.c:304:8: warning: variable ‘circuit’ set but not used [-Wunused-but-set-variable]
  char  circuit = FALSE;  // flag circuit active
        ^~~~~~~
postpuff.c:302:8: warning: variable ‘parts’ set but not used [-Wunused-but-set-variable]
  char  parts = FALSE;   // flag part-Beschreibung active
        ^~~~~
```