Those kernel files were being directly accessed, which we're not
allowing anymore to avoid that changes in the kernel side break tooling.

Warn if these copies drift from the original files.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Eric Auger <eric.auger@linaro.org>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Yunlong Song <yunlong.song@huawei.com>
Link: http://lkml.kernel.org/n/tip-mnopguymhnwzjhw3mowllvsy@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>