jruby - security update

JRuby before 1.6.5.1 computes hash values without restricting the ability to
trigger hash collisions predictably, which allows context-dependent attackers
to cause a denial of service (CPU consumption) via crafted input to an
application that maintains a hash table. Note: This update includes
corrections to the original fix for later Debian releases to avoid the issues
identified in CVE-2012-5370.