Make sure that we don't free the SCTP shared key too early.
Thanks to Pouyan Sepehrdad from Qualcomm Product Security Initiative
for reporting the issue.
This syns the sources with the Yosemite sources.


git-svn-id: http://sctp-refimpl.googlecode.com/svn/trunk/KERN/usrsctp/usrsctplib@9215 9df1edf5-d72c-5b5f-11c0-5f5209eb73f7