Add patch on prevent premature hsplit for Perl 5.8.[89], 5.10.1, 5.12.5

[hirose31]

Add "Prevent premature hsplit() calls, and only trigger REHASH after hsplit()" patch for following EOL perls.

• 5.8.8, 5.8.9
• 5.10.1
• 5.12.5

[tokuhirom]

+1

[bingos]

Before I merge this, could I have some more information on what issue it is that this is trying to fix please.

Many thanks.

[hirose31]

@bingos This patch is to fix CVE-2013-1667

• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1667

The rehash mechanism in Perl 5.8.2 through 5.16.x allows context-dependent attackers to cause a denial of service (memory consumption and crash) via a crafted hash key.

At Perl 5.16.3 and 5.14.4, this issue has already been fixed. On the other hand, EOL Perls (5.8, 5.10, 5.12) also have been fixed in repository but I think it will not release.

I think it is not good that users install perl with vulnerability so I pull request.

[hirose31]

Thanks a lot! (Arigatou gozaimasu!)