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>

net/dcb/dcbevent.c

@@ -19,6 +19,7 @@
 
 #include <linux/rtnetlink.h>
 #include <linux/notifier.h>
+#include <linux/export.h>
 
 static ATOMIC_NOTIFIER_HEAD(dcbevent_notif_chain);