Pauli Saksa

I bundled another bugfix from the same area of code to this PR: When `TcpConnector` is destroyed and it deallocates its list of endpoints, those endpoints call `TcpConnector::onEndPointClosed()` with bad...

Note that this fix breaks "3rdparty/flow" build. I don't really know what to do with that. "3rdparty/flow" has its own copy of fmt (in "3rdparty/flow/3rdparty/fmt") which seems to be unused....