Smack: Make the syslog control configurable

Smack: Make the syslog control configurable

The syslog control requires that the calling proccess
have the floor ("_") Smack label. Tizen does not run any
processes except for kernel helpers with the floor label.
This changes allows the admin to configure a specific
label for syslog. The default value is the star ("*")
label, effectively removing the restriction. The value
can be set using smackfs/syslog for anyone who wants
a more restrictive behavior.

Change-Id: Ia4270bf8864bd8342e585bbdd4791fb8359e8916
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>