Smack: Assign smack_known_web label for kernel thread's socket in the sk_alloc_securi...

Smack: Assign smack_known_web label for kernel thread's socket in the sk_alloc_security hook

Creating struct sock by sk_alloc function in various kernel subsystems
like bluetooth dosen't call smack_socket_post_create(). In such case,
received sock label is the floor('_') label and makes access deny.

Refers to:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7412301b76bd53ee53b860f611fc3b5b1c2245b5

Change-Id: I614c5f0e6d59be5ca6b49f0581edfef79fc334cf
Signed-off-by: jooseong lee <jooseong.lee@samsung.com>