runner/resume: change exit code for results gen fail

When results generation fails exit with code 3, it will help
to differentiate from failed exection at resume runs. Added
also some debug messages at different error points.

Cc: Petri Latvala <adrinael@adrinael.net>
Signed-off-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Reviewed-by: Petri Latvala <adrinael@adrinael.net>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>