ipv6: Kill ipv6 dependency of icmpv6_send().

Following patch adds icmp-registration module for ipv6.  It allows
ipv6 protocol to register icmp_sender which is used for sending
ipv6 icmp msgs.  This extra layer allows us to kill ipv6 dependency
for sending icmp packets.

This patch also fixes ip_tunnel compilation problem when ip_tunnel
is statically compiled in kernel but ipv6 is module

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile
index 309af19..9af088d 100644
--- a/net/ipv6/Makefile
+++ b/net/ipv6/Makefile
@@ -40,7 +40,7 @@
 obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
 obj-$(CONFIG_IPV6_GRE) += ip6_gre.o
 
-obj-y += addrconf_core.o exthdrs_core.o ip6_checksum.o
+obj-y += addrconf_core.o exthdrs_core.o ip6_checksum.o ip6_icmp.o
 obj-$(CONFIG_INET) += output_core.o protocol.o $(ipv6-offload)
 
 obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o