Remove support for libjingle
It's a third party library originally provided by Google. AFAICT it was used to interoperate with Google Talk. It appears Google dropped it though and I can't even find where the source lives today. Considering they discontinued their Google Talk app in 2013 and subsequently shut down the service completely on June 16th 2022 [1] that's not surprising though. Furthermore our copy of libjingle fails to build with openssl >= 1.1, while downstream distros seems to have patched that, openssl >=3 introduces another build failure. In addition the code only builds with older versions of mediastreamer, libortp and srtp (there's an old patch on phabricator [2], which addresses parts of that, but it has never landed despite being accepted).
BUG: 463997 BUG: 407543 BUG: 368340 BUG: 399678
[1] https://support.google.com/talk/ [2] https://phabricator.kde.org/D15956