openswan: security bump to version 2.6.40

Fixes CVE-2013-6466.
openswan-wno-error-cpp.patch is no longer required since it's now
conditional on a check for a modern enough compiler.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>