kill: Fix kill tests
kill: Fix kill tests

runc was failing with our kill test.

- Only SIGKILL and SIGSTOP can not be caught, blocked or ignored, skip
  signals that are not forwared by cc-shim.

- Show the signal name when running the tests (not only number).

Fixes: #640

Signed-off-by: Jose Carlos Venegas Munoz <821ab150128e889cb3ad9aab6e72689fd9ad26f2@intel.com>

MarioCarrilloA/tests,chavafg/tests,clearcontainers/tests,devimc/tests,clearcontainers/tests,MarioCarrilloA/tests,devimc/tests,chavafg/tests