Use GQueue for RedCharDevice::send_queue
Use GQueue for RedCharDevice::send_queue

There was an extra RedCharDeviceMsgToClientItem type whose only
purpose was to manage a linked list of items to send. GQueue has the
same purpose as this type in addition to being generic. As the length of
the send queue is tracked, a GQueue is more appropriate than a GList and
allow to remove RedCharDevice::send_queue_size.

Acked-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

fgouget/spice,fgouget/spice,fgouget/spice,fgouget/spice