ext/sockets: adding IPPROTO_ICMP* constants for socket creations.

Is to create socket for Internet Control Message Protocol context.
Due to their nature, they are meant to be used via
raw sockets rather than TCP/UDP.

Author: devnexen

ext/sockets/sockets.stub.php

@@ -1647,6 +1647,20 @@
  */
 const SOL_UDPLITE = UNKNOWN;
 #endif
+#ifdef IPPROTO_ICMP
+/**
+ * @var int
+ * @cvalue IPPROTO_ICMP
+ */
+const IPPROTO_ICMP = UNKNOWN;
+#endif
+#ifdef IPPROTO_ICMPV6
+/**
+ * @var int
+ * @cvalue IPPROTO_ICMPV6
+ */
+const IPPROTO_ICMPV6 = UNKNOWN;
+#endif
 
 #ifdef HAVE_IPV6
 /**