net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules

These files are non modular, but need to export symbols using
the macros now living in export.h -- call out the include so
that things won't break when we remove the implicit presence
of module.h from everywhere.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 30fcee4..8027413 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -3,6 +3,7 @@
 #include <linux/ipv6.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv6.h>
+#include <linux/export.h>
 #include <net/dst.h>
 #include <net/ipv6.h>
 #include <net/ip6_route.h>