[ticket/12660] Improve check for when phpinfo() is disabled.

PHPBB3-12660
Merge pull request #2548 from bantu/ticket/12660

[ticket/12660] Improve check for when phpinfo() is disabled.
Merge branch 'develop-olympus' into develop-ascraeus

# By Andreas Fischer
# Via Andreas Fischer (1) and Dhruv Goel (1)
* develop-olympus:
  [ticket/12660] Improve check for when phpinfo() is disabled.