openssh: Update from 6.2p2 -> 6.4p1

This patch also bumps up the HPN version of openssh so that it compiles
on top of 6.4. Along with the bump, a package was added for the high
performance networking version.

The gcmrekey patch was removed as this vulnerability is fixed in
version 6.4 onward. http://www.openssh.org/txt/gcmrekey.adv
Merge pull request #1426 from wkennington/openssh

openssh: Update from 6.2p2 -> 6.4p1