Register signal handler to kernel if not claimed

To set special handler for a signal, if the signal was not
claimed before, the default handler in sigchain must be registerred
for it before claimimg it in sigchain.

Change-Id: I7ab74392cabb7f34af8ae038c90d20f0641b9d99
Signed-off-by: jgu21 <jinghui.gu@intel.com>