Revision bump for 2.9.6

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Hrvoje Ribicic <riba@google.com>

configure.ac

 # Configure script for Ganeti
 m4_define([gnt_version_major], [2])
 m4_define([gnt_version_minor], [9])
-m4_define([gnt_version_revision], [5])
+m4_define([gnt_version_revision], [6])
 m4_define([gnt_version_suffix], [])
 m4_define([gnt_version_full],
           m4_format([%d.%d.%d%s],