LU-6215 kernel: report 4.2.1 kernel support

Add to the Lustre ChangeLog file support for 4.2.1 linux
kernels for clients and servers in the case of using the
latest ZFS backend.

Change-Id: If126c6c1dc8e46e0485f04090590759dc2eb1587
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/16769


Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>