migration: cpr helpers

Add the cpr_incoming_needed, cpr_open_fd, and cpr_resave_fd helpers,
for use when adding cpr support for vfio and iommufd.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/1749569991-25171-2-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
2 files changed