mb_encode_mimeheader() attempts to return a void from Patchwork\PHP\Shim\mb_encode_mimeheader()

[Donatello-za]

The mb_encode_mimeheader() function in Utf8/Bootup/mbstring.php returns with a result from Patchwork\PHP\Shim\mb_encode_mimeheader() in PHP/Shim/Mbstring.php but Patchwork\PHP\Shim\mb_encode_mimeheader() itself actually returns a void. This produces code inspection warnings and possible bugs.

[nicolas-grekas]

Closing as "won't fix": the fact that this has no return value is because the shim has no implementation. If it had one, it would return a string.