conf: Disk 'shared' state is not guest ABI

Drop the checking of 'shared' from the ABI stability check. This
property controls whether the hypervisor allows concurrent access to the
same file, but this fact does not influence guest ABI.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>

src/conf/domain_conf.c

@@ -20820,8 +20820,7 @@ virDomainDiskDefCheckABIStability(virDomainDiskDefPtr src,
 
     }
 
-    if (src->src->readonly != dst->src->readonly ||
-        src->src->shared != dst->src->shared) {
+    if (src->src->readonly != dst->src->readonly) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                        _("Target disk access mode does not match source"));
         return false;