[packages] openssh: update to 6.4p1

This release fixes a security bug:

 * sshd(8): fix a memory corruption problem triggered during rekeying
   when an AES-GCM cipher is selected. Full details of the vulnerability
   are available at: http://www.openssh.com/txt/gcmrekey.adv

Signed-off-by: Peter Wagner <tripolar@gmx.at>


git-svn-id: svn://svn.openwrt.org/openwrt/packages@38693 3c298f89-4303-0410-b956-a3cf2f4a3e73