jdk8-openjdk: sandbox escape

It was discovered that the security fix for CVE-2013-5838 was incomplete
and still allowed remote attackers to escape the Java security sandbox
mechanism.
The root problem is that the Reflection API does not properly guarantee
type safety when Method Handle objects were invoked across two different
Class Loader namespaces.
A part of the original patch was to use the "loadersAreRelated()" method
to ensure that the two Class Loaders are related, which is a condition
for correct type safety.
However, this condition could be easily fulfilled by abusing certain
behaviors in the class loading process, which could allow an attacker
to bypass the type safety checks and ultimately escape the security
sandbox mechanism.