MFC r258737

In keg_dtor(), print out the keg name in the "Freed UMA keg was not empty"
message printed to the console.  This makes it easier to track down
the source of certain memory leaks.

Suggested by: adrian
Approved by: re (gjb)
MFC r258588

In sys/netpfil/ipfw/ip_fw_nat.c:vnet_ipfw_nat_uninit() we call "IPFW_WLOCK(chain);".
This lock gets deleted in sys/netpfil/ipfw/ip_fw2.c:vnet_ipfw_uninit().

Therefore, vnet_ipfw_nat_uninit() *must* be called before vnet_ipfw_uninit(),
but this doesn't always happen, because the VNET_SYSINIT order is the same for both functions.
In sys/net/netpfil/ipfw/ip_fw2.c and sys/net/netpfil/ipfw/ip_fw_nat.c,
IPFW_SI_SUB_FIREWALL == IPFW_NAT_SI_SUB_FIREWALL == SI_SUB_PROTO_IFATTACHDOMAIN
and
IPFW_MODULE_ORDER == IPFW_NAT_MODULE_ORDER

Consequently, if VIMAGE is enabled, and jails are created and destroyed,
the system sometimes crashes, because we are trying to use a deleted lock.

To reproduce the problem:
  (1)  Take a GENERIC kernel config, and add options for: VIMAGE, WITNESS,
       INVARIANTS.
  (2)  Run this command in a loop:
       jail -l -u root -c path=/ name=foo persist vnet && jexec foo ifconfig lo0 127.0.0.1/8 && jail -r foo

       (see http://lists.freebsd.org/pipermail/freebsd-current/2010-November/021280.html )

Fix the problem by increasing the value of IPFW_NAT_SI_SUB_FIREWALL,
so that vnet_ipfw_nat_uninit() runs after vnet_ipfw_uninit().

Approved by: re (gjb)
MFC 258591
In vnet_route_uninit(), free some memory that is allocated in vnet_route_init().

To reproduce the problem:
  (1)  Take a GENERIC kernel config, and add options for: VIMAGE, WITNESS,
       INVARIANTS.
  (2)  Run this command in a loop:
       jail -l -u root -c path=/ name=foo persist vnet && jexec foo ifconfig lo0 127.0.0.1/8 && jail -r foo

       see: http://lists.freebsd.org/pipermail/freebsd-current/2010-November/021280.html
            http://lists.freebsd.org/pipermail/freebsd-current/2010-November/021291.html

This doesn't eliminate all the "Freed UMA keg was not empty" warning messages
on the console, but it helps.

Approved by: re (gjb)