restrict warning
restrict warning

```
system.c:58:15: warning: unused variable 'map' [-Wunused-variable]
        ctr_map*     map = NULL;
                     ^
1 warning generated.
```

takano32/citrine,gabordemooij/citrine,gabordemooij/citrine,takano32/citrine,gabordemooij/citrine,takano32/citrine