wireshark: s/tvb_length/tvb_captured_length/

In wireshak commit 22149c55 (v.1.11.3) the API was renamed.
Follow the change in our code too. Since the wireshark change was
made in the very same version that we require at least we are
good to go.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

tools/wireshark/src/packet-libvirt.c

@@ -338,7 +338,7 @@ dissect_libvirt_payload(tvbuff_t *tvb, proto_tree *tree,
 {
     gssize payload_length;
 
-    payload_length = tvb_length(tvb) - VIR_HEADER_LEN;
+    payload_length = tvb_captured_length(tvb) - VIR_HEADER_LEN;
     if (payload_length <= 0)
         return; /* No payload */
 
@@ -405,7 +405,7 @@ dissect_libvirt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
         proto_item *ti;
         proto_tree *libvirt_tree;
 
-        ti = proto_tree_add_item(tree, proto_libvirt, tvb, 0, tvb_length(tvb), ENC_NA);
+        ti = proto_tree_add_item(tree, proto_libvirt, tvb, 0, tvb_captured_length(tvb), ENC_NA);
         libvirt_tree = proto_item_add_subtree(ti, ett_libvirt);
 
         offset = 0;