include: refresh linux header copies in the tree

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/linux/Makefile.am b/include/linux/Makefile.am
index 082198e..ff5770d 100644
--- a/include/linux/Makefile.am
+++ b/include/linux/Makefile.am
@@ -1 +1,2 @@
-noinst_HEADERS = gtp_nl.h
+noinst_HEADERS = gtp.h		\
+		 if_link.h