vmstate static checker: detect section renames

Commit 292b1634 changed the section name of "ICH9 LPC" to "ICH9-LPC",
and that causes the static checker to flag this:

Section "ICH9 LPC" does not exist in dest

This patch introduces a function that checks for section renames and
also a dictionary that maps those renames.

Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

---
This is a small patch to a script; doesn't break qemu and helps with the
static checker, so it's a very low-risk patch for 2.1.
virtio-serial-bus: keep port 0 reserved for virtconsole even on unplug

We keep port 0 reserved for compat with older guests, where only
virtio-console was expected.  Even if a system is started without a
virtio-console port, port #0 is kept aside.  However, after a
virtconsole port is unplugged, port id 0 became available, and the next
hotplug of a virtserialport caused failure due to it not being a console
port.

Steps to reproduce:

$ ./x86_64-softmmu/qemu-system-x86_64 -m 512 -cpu host -enable-kvm -device virtio-serial-pci -monitor stdio  -vnc :1
QEMU 2.0.91 monitor - type 'help' for more information
(qemu) device_add virtconsole,id=p1
(qemu) device_del p1
(qemu) device_add virtserialport,id=p1
Port number 0 on virtio-serial devices reserved for virtconsole devices for backward compatibility.
Device 'virtserialport' could not be initialized
(qemu) quit

Reported-by: dengmin <mdeng@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Merge remote-tracking branch 'remotes/amit/for-2.1' into staging

* remotes/amit/for-2.1:
  virtio-serial-bus: keep port 0 reserved for virtconsole even on unplug

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Merge remote-tracking branch 'remotes/amit-migration/for-2.1' into staging

* remotes/amit-migration/for-2.1:
  vmstate static checker: detect section renames

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
cadence_uart: check for serial backend before using it.

This checks that s->chr is not NULL before using it.

Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>