Bug#4125 - mod_lang should provide way to reject illegall-encoded filenames.
Forgot to actually wire up the handling of the RequireValidEncoding LangOption
to the propagation of decoding errors; without this, all illegal encodings
would be rejected.
Copy-pasto.
Use updated Encode API for getting/setting policy.
Merge pull request #66 from proftpd/lang-require-valid-encoding-bug4125

Bug#4125 - mod_lang should provide way to reject illegally-encoded filenames.