[IPSEC]: Add async resume support on output

This patch adds support for async resumptions on output.  To do so,
the transform would return -EINPROGRESS and subsequently invoke the
function xfrm_output_resume to resume processing.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index ab9e747..9967720 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1119,6 +1119,7 @@
 extern int xfrm_state_mtu(struct xfrm_state *x, int mtu);
 extern int xfrm_init_state(struct xfrm_state *x);
 extern int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb);
+extern int xfrm_output_resume(struct sk_buff *skb, int err);
 extern int xfrm_output(struct sk_buff *skb);
 extern int xfrm4_extract_header(struct sk_buff *skb);
 extern int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb);