qemu: Move freeing of PCI address list to qemuProcessStop

Rather than freeing the list before starting a new VM clear it after
stopping the old instance when the data becomes invalid.

(cherry picked from commit 44f8e00b)

src/qemu/qemu_domain_address.c

@@ -2221,7 +2221,6 @@ qemuDomainAssignPCIAddresses(virDomainDefPtr def,
     if (obj && obj->privateData) {
         priv = obj->privateData;
         /* if this is the live domain object, we persist the PCI addresses */
-        virDomainPCIAddressSetFree(priv->pciaddrs);
         priv->pciaddrs = addrs;
         addrs = NULL;
     }

src/qemu/qemu_process.c

@@ -6438,6 +6438,8 @@ void qemuProcessStop(virQEMUDriverPtr driver,
     priv->autoCpuset = NULL;
 
     /* remove address data */
+    virDomainPCIAddressSetFree(priv->pciaddrs);
+    priv->pciaddrs = NULL;
     virDomainUSBAddressSetFree(priv->usbaddrs);
     priv->usbaddrs = NULL;