sctp: avoid to repeatedly declare external variables

Move the declaration for external variables to sctp.h file avoiding
to repeatedly declare them with extern keyword.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 856f01c..c56a438 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -166,6 +166,9 @@
   */
 extern struct kmem_cache *sctp_chunk_cachep __read_mostly;
 extern struct kmem_cache *sctp_bucket_cachep __read_mostly;
+extern long sysctl_sctp_mem[3];
+extern int sysctl_sctp_rmem[3];
+extern int sysctl_sctp_wmem[3];
 
 /*
  *  Section:  Macros, externs, and inlines