[ticket/10404] Use anonymous function instead of create_function in acp/auth

PHPBB3-10404
[ticket/10404] Fix codesniffer complaint about anonymous function

PHPBB3-10404
Merge pull request #2832 from marc1706/ticket/10404

[ticket/10404] Use anonymous function instead of create_function in acp/auth

* marc1706/ticket/10404:
  [ticket/10404] Fix codesniffer complaint about anonymous function
  [ticket/10404] Use anonymous function instead of create_function in acp/auth