SCTP: Fix local_addr deletions during list traversals.

SCTP: Fix local_addr deletions during list traversals.

Upstream commit: 22626216c46f2ec86287e75ea86dd9ac3df54265

Since the lists are circular, we need to explicitely tag
the address to be deleted since we might end up freeing
the list head instead.  This fixes some interesting SCTP
crashes.

Signed-off-by: Chidambar 'ilLogict' Zinnoury <illogict@online.fr>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>