Passing QDBusUnixFileDescriptors over peer-to-peer connections currently
does not work, because QDBusConnectionPrivate::setPeer() does not set
this->capabilities (unlike QDBusConnectionPrivate::setConnection()
which is executed for bus connections).
Keep track of whether the connection already has been authenticated, and
once the connection does get authenticated, update this->capabilities.
Note that sending a message directly after connecting (before any
message has been received from the peer) might still fail if the message
contains a QDBusUnixFileDescriptor.
Pick-to: 5.15
Fixes: QTBUG-85396
Change-Id: Ib83213ebcd3255fb091c6faefb3618745b8d736c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
6d880185b1