[ticket/12746] Init phpbb_dispatcher being used by delete_post()

PHPBB3-12746
Merge pull request #2626 from dhruvgoel92/ticket/12746

[ticket/12746] Init phpbb_dispatcher being used by delete_post()

* dhruvgoel92/ticket/12746:
  [ticket/12746] Init phpbb_dispatcher being used by delete_post()