netfilter: nf_conntrack: connection tracking helper name persistent aliases

This patch adds the macro MODULE_ALIAS_NFCT_HELPER that defines a
way to provide generic and persistent aliases for the connection
tracking helpers.

This next patch requires this patch.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index b76a868..f11255e 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -298,5 +298,8 @@
 	local_bh_enable();				\
 } while (0)
 
+#define MODULE_ALIAS_NFCT_HELPER(helper) \
+        MODULE_ALIAS("nfct-helper-" helper)
+
 #endif /* __KERNEL__ */
 #endif /* _NF_CONNTRACK_H */