ipfw: Add sysctl flag CTLFLAG_TUN to loader tunables
The following sysctl variables are actually loader tunables. Add sysctl
flag CTLFLAG_TUN to them so that sysctl -T will report them correctly.
- net.inet.ip.fw.enable
- net.inet6.ip6.fw.enable
- net.link.ether.ipfw
No functional change intended.
Reviewed by: glebius
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D41928
(cherry picked from commit 49197c391b3d49a33bcd08471bf64d533cd10f9d)