Update IPPROTO_* constants

* xlat/inet_protocols.in: Add IPPROTO_MPLS.
diff --git a/xlat/inet_protocols.in b/xlat/inet_protocols.in
index 6092f2b..b7e13c9 100644
--- a/xlat/inet_protocols.in
+++ b/xlat/inet_protocols.in
@@ -28,5 +28,6 @@
 IPPROTO_COMP
 IPPROTO_SCTP
 IPPROTO_UDPLITE
+IPPROTO_MPLS
 IPPROTO_RAW
 IPPROTO_MAX