This patch deletes the flexible-array skip[] from the structure
sctp_ifwdtsn/fwdtsn_hdr to avoid some sparse warnings:
  # make C=2 CF="-Wflexible-array-nested" M=./net/sctp/
  net/sctp/stream_interleave.c: note: in included file (through include/net/sctp/structs.h, include/net/sctp/sctp.h):
  ./include/linux/sctp.h:611:32: warning: nested flexible array
  ./include/linux/sctp.h:628:33: warning: nested flexible array
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
 struct sctp_fwdtsn_hdr {
        __be32 new_cum_tsn;
-       struct sctp_fwdtsn_skip skip[];
+       /* struct sctp_fwdtsn_skip skip[]; */
 };
 
 struct sctp_fwdtsn_chunk {
 
 struct sctp_ifwdtsn_hdr {
        __be32 new_cum_tsn;
-       struct sctp_ifwdtsn_skip skip[];
+       /* struct sctp_ifwdtsn_skip skip[]; */
 };
 
 struct sctp_ifwdtsn_chunk {
 
 _sctp_walk_fwdtsn((pos), (chunk), ntohs((chunk)->chunk_hdr->length) - sizeof(struct sctp_fwdtsn_chunk))
 
 #define _sctp_walk_fwdtsn(pos, chunk, end)\
-for (pos = chunk->subh.fwdtsn_hdr->skip;\
-     (void *)pos <= (void *)chunk->subh.fwdtsn_hdr->skip + end - sizeof(struct sctp_fwdtsn_skip);\
+for (pos = (void *)(chunk->subh.fwdtsn_hdr + 1);\
+     (void *)pos <= (void *)(chunk->subh.fwdtsn_hdr + 1) + end - sizeof(struct sctp_fwdtsn_skip);\
      pos++)
 
 /* External references. */
 
 }
 
 #define _sctp_walk_ifwdtsn(pos, chunk, end) \
-       for (pos = chunk->subh.ifwdtsn_hdr->skip; \
-            (void *)pos <= (void *)chunk->subh.ifwdtsn_hdr->skip + (end) - \
+       for (pos = (void *)(chunk->subh.ifwdtsn_hdr + 1); \
+            (void *)pos <= (void *)(chunk->subh.ifwdtsn_hdr + 1) + (end) - \
                            sizeof(struct sctp_ifwdtsn_skip); pos++)
 
 #define sctp_walk_ifwdtsn(pos, ch) \