Add SELinux policy capability for always checking packet and peer classes.

Currently the packet class in SELinux is not checked if there are no
SECMARK rules in the security or mangle netfilter tables.  Some systems
prefer that packets are always checked, for example, to protect the system
should the netfilter rules fail to load or if the nefilter rules
were maliciously flushed.

Add the always_check_network policy capability which, when enabled, treats
SECMARK as enabled, even if there are no netfilter SECMARK rules and
treats peer labeling as enabled, even if there is no Netlabel or
labeled IPSEC configuration.

Includes definition of "redhat1" SELinux policy capability, which
exists in the SELinux userpace library, to keep ordering correct.

The SELinux userpace portion of this was merged last year, but this kernel
change fell on the floor.

Signed-off-by: Chris PeBenito <cpebenito@tresys.com>
Signed-off-by: Eric Paris <eparis@redhat.com>