Log Message:
news/leafnode: Update to 1.11.12

Removed patches that were merged upstream.
Take maintainership.

===========================================================================
* 1.11.12, 2021-03-28

### CHANGES
- The sourceforge.net hosting was reconfigured to serve HTTPS, thus, the
  leafnode website is now at https://leafnode.sourceforge.io/
- https://www.leafnode.org/ is now being served by an external nginx-based
  web server so it can use a proper TLS certificate.
- The GMANE links and last modified tag have been removed from the
  website.
- The web site has been updated to use newer https:// links where
  available.
- The mailing list has been moved to the leafnode.org domain. See README.

### BUGFIXES
- A configuration --without-ipv6 now compiles again.
  Patch by Michael Bäuerle.
- Leafnode recognizes an EEXIST error to rmdir() the same as ENOTEMPTY.
  Patch by Gary R. Schmidt.
- Leafnode no longer trashes the stack if it, while scanning the message.id
  directory, finds a directory with an all-numeric name that is 1000 or
  higher. Reported by Matthias Gerstner.

===========================================================================