openssl: fix a 4 year old "use-after-free" problem

https://rt.openssl.org/Ticket/Display.html?id=2167
http://www.tedunangst.com/flak/post/analysis-of-openssl-freelist-reuse
http://ftp.openbsd.org/pub/OpenBSD/patches/5.4/common/008_openssl.patch

Obtained from:	OpenBSD