IPSEC-GRE: fixes and API update to common types.

Change-Id: Icdcbac7453baa837a9c0c4a2401dff4a6aa6cba0
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/ipsec/esp_decrypt.c b/src/vnet/ipsec/esp_decrypt.c
index 3e09d9d..c6cb439 100644
--- a/src/vnet/ipsec/esp_decrypt.c
+++ b/src/vnet/ipsec/esp_decrypt.c
@@ -396,7 +396,7 @@
 	    }
 	}
 
-      if (vnet_buffer (b[0])->ipsec.flags & IPSEC_FLAG_IPSEC_GRE_TUNNEL)
+      if (PREDICT_FALSE (ipsec_sa_is_set_IS_GRE (sa0)))
 	next[0] = ESP_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 
     trace: