Scapy upgrade to 2.4.0.rc5

- many of the patches fd.io applies in test/patches/2.3.3 are now upstreamed in 2.4
- 2.4 adds support for IGMPv3 which is my main motivation for the upgrade

Change-Id: If2c0a524e3cba320b4a5d8cd07817c6ea2bf0c5a
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/test/patches/scapy-2.4/mpls.py.patch b/test/patches/scapy-2.4/mpls.py.patch
new file mode 100644
index 0000000..2a8fc84
--- /dev/null
+++ b/test/patches/scapy-2.4/mpls.py.patch
@@ -0,0 +1,21 @@
+diff --git a/scapy/contrib/mpls.py b/scapy/contrib/mpls.py
+index 8daddf2..a9dc7fe 100644
+--- a/scapy/contrib/mpls.py
++++ b/scapy/contrib/mpls.py
+@@ -18,6 +18,7 @@
+ from scapy.packet import Packet, bind_layers, Padding
+ from scapy.fields import BitField,ByteField
+ from scapy.layers.inet import IP
++from scapy.contrib.bier import BIER
+ from scapy.layers.inet6 import IPv6
+ from scapy.layers.l2 import Ether, GRE
+ from scapy.compat import orb
+@@ -36,6 +37,8 @@ class MPLS(Packet):
+            ip_version = (orb(payload[0]) >> 4) & 0xF
+            if ip_version == 4:
+                return IP
++           elif ip_version == 5:
++               return BIER
+            elif ip_version == 6:
+                return IPv6
+        return Padding