Introduce two new patches that revert the conflicting part of the

Introduce two new patches that revert the conflicting part of the
maildir-mtime patch before applying the sidebar patch, and afterwards
re-apply the relevant bits. This mitigates the chance of bugs being
introduced when manually resolving conflicts with new versions of the
sidebar patch. This fixes new mail detection in the mutt-patched package.
(Closes: #484537, #484538)