[ticket/13270] Make m_softdelete perm global for boards updated from 3.0.12.

PHPBB3-13270
Merge pull request #3118 from prototech/ticket/13270

[ticket/13270] Make m_softdelete perm global for boards updated from 3.0.12.

* prototech/ticket/13270:
  [ticket/13270] Make m_softdelete perm global for boards updated from 3.0.12.