Fix translation extraction script

Exclude BULLET_PULLING entries in json from translation because it does not contain any translatable thing.

Fix missing parameter `infilename` (seems to be gone lost with 4ee95d35c6c21601c9abd19778d38ed7b32f32da). This would lead to a error when a modinfo does not contain any translatable string. Example valid modinfo.json :
```
[ {"type":"MOD_INFO", "ident":"a"} ]
```