libssh: fix CVE-2014-0017

Integrate community fix for the issue CVE-2014-0017

Signed-off-by: Priyanka Shobhan <priyanka_shobhan@mentor.com>
Merge pull request #185 from pshobhan/pshobhan/bugfixes/SB-2689

libssh: fix CVE-2014-0017