BUG/MEDIUM: connections: Let the xprt layer know a takeover happened.

When we takeover a connection, let the xprt layer know. If it has its own
tasklet, and it is already scheduled, then it has to be destroyed, otherwise
it may run the new mux tasklet on the old thread.

Note that we only do this for the ssl xprt for now, because the only other
one that might wake the mux up is the handshake one, which is supposed to
disappear before idle connections exist.

No backport is needed, this is for 2.2.
5 files changed