lib: Add argc/argv to igt_simple_init

lib: Add argc/argv to igt_simple_init

There's a pile of ideas around to add generally useful options like
--debug to all igt tests. Or unify the runtime behaviour between
simple and subtest tests a bit more.

The first step to get there is to add argc/argv to igt_simple_init so
that we can get at the argument list.

Cc: Tim Gore <tim.gore@intel.com>
Cc: Thomas Wood <thomas.wood@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>