Windows 10 RDS is quite relaxed about missing channel join PDUs,
whereas we have to adhere quite tightly to the specification to
make sure we get a TLS "Client hello" where appropriate. This makes
us incompatible with older RDP clients. For example, the Wyse sx0
thin client does not send a channel join PDU for the user channel.
Older, non-TLS versions of xrdp supported these devices.
This commit re-implements the xrdp v0.6.1 behaviour for non-TLS
connections only, allowing system administrators to use these devices
on trusted networks. These devices are in any case too old to
establish a modern TLS connection.
8fdc1ba216