Add a new spice chardev to allow arbitrary communication between the
host and the Spice client via the spice server.
Examples:
This allows the Spice client to have a special port for the qemu
monitor:
... -chardev spiceport,name=org.qemu.monitor,id=monitorport
-mon chardev=monitorport
v2:
- remove support for chardev to chardev linking
- conditionnaly compile with SPICE_SERVER_VERSION
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>