LU-2675 cleanup: define sparse annotations for libcfs

LU-2675 cleanup: define sparse annotations for libcfs

Add empty definitions for the sparse checker annotations (__user,
__kernel, __safe, ...) defined by the kernel. This will allow these
annotations to be used in files common to kernel modules and libcfs.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I26a7d3fad0bc07535db4dfaa25e40bb10ff4e951
Reviewed-on: http://review.whamcloud.com/6969
Tested-by: Hudson
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Sebastien Buisson <sebastien.buisson@bull.net>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>