power_BacklightServer: support lkdtm

This adds support for the lkdtm crash interface, if it is available.

BUG=chromium:215167
TEST=None

Change-Id: I63dfb7823fc7c55d6692b83686f0df6115f7ef28
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/59966
Reviewed-by: Jim Hebert <jimhebert@chromium.org>
1 file changed