spapr: skip configuration section during migration of older machines

spapr: skip configuration section during migration of older machines

Since QEMU 2.4, we have a configuration section in the migration stream.
This must be skipped for older machines, like it is already done for x86.

This patch fixes the migration of pseries-2.3 from/to QEMU 2.3, but it
breaks migration of the same machine from/to QEMU 2.4/2.4.1/2.5. We do
that anyway because QEMU 2.3 is likely to be more widely deployed than
newer QEMU versions.

Fixes: 61964c23e5ddd5a33f15699e45ce126f879e3e33
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit 09b5e30da5b19f44768a5429f603caaede216757)

Conflicts:
	hw/ppc/spapr.c

*remove dep on 5013c5474

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>