netfilter: Fix SCTP nat build.

We need to select LIBCRC32C.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/Kconfig

@@ -259,6 +259,7 @@ config NF_NAT_PROTO_SCTP
 	tristate
 	default NF_NAT && NF_CT_PROTO_SCTP
 	depends on NF_NAT && NF_CT_PROTO_SCTP
+	select LIBCRC32C
 
 config NF_NAT_FTP
 	tristate