[ticket/12332] Fix plupload attachments with long names overflow

PHPBB3-12332
Merge pull request #2638 from VSEphpbb/ticket/12332

[ticket/12332] Fix plupload attachments with long names

* VSEphpbb/ticket/12332:
  [ticket/12332] Fix plupload attachments with long names overflow
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12332] Fix plupload attachments with long names overflow