Change smack label of /opt/etc from floor to System::Shared

Change smack label of /opt/etc from floor to System::Shared

Since daemon running with "System" smack label needs to write/create file into /opt/etc in runtime, change smack label of /opt/etc/ from floor to "System::Shared"

Only daemon running as "System" label can write file.
(Accepted smack rule : System System::Shared rwxat)
On the other hand, daemon running as "User" label cannot write, only can read.
(Accepted smack rule : User System::Shared rxl)

Change-Id: I950d3eee2504a7d0432d0063a206cea669febcd3
Signed-off-by: Seongwook Chung <seong.chung@samsung.com>