Update distsigkey with GnuPG's version
* packages/distsigkey.gpg: Use GnuPG's distsigkey.gpg file.
The distsigkey.gpg was taken from GnuPG Version
18e94c72294a437b982a796704fe6f78c776db2e
(cherry picked from commit 1c5a17fd1e19899af324559c8fba4f1f865d8cd2)