vr: Remove extra VR_ISR_RX_NOBUF test

Pointed-out-by: swildner@
tcp: Cache align tcp_stats

- tcp_stats is padded to multiple cache line size; add comment about it
- Cache align the per-cpu tcp_stats array
kernel/acpi: Fix -Wundef.
kernel/wlan: Fix -Wundef.
kernel/virtio: Fix -Wundef.
kernel/mfi: Move the dereference of 'sc' below the NULL check.
kernel/ed: Fix -Wundef.
kernel/em/emx: Fix -Wundef.
bsd.kern.mk: -Wno-unused-but-set-variable is gcc47 specific.
natacontrol(8): s/atacontrol/natacontrol/
natacontrol(8): Add commands to tweak power/acoustic management features.

Sometimes disks designed to operate in low power mode by default
constantly spin up/down during operation which leads to reduced
performance.

This commit adds the 'feature' command to natacontrol(8) which
can be used to tweak the 'advanced power management' and 'automatic
acoustic management' features. Their current setting could already
be viewed before this commit using the 'natacontrol cap' command.

I'd like this to be possible with camcontrol(8) too for CAM attached
disks, but afaict these are ATA specific features so I guess we'd
have to integrate ATA into CAM too before that is possible.

Dragonfly-bug: <http://bugs.dragonflybsd.org/issues/2531>
Reported-by:   Maurizio Lombardi <m.lombardi85@gmail.com>
Taken-from:    FreeBSD PR 81692
Tested-by:     Maurizio Lombardi <m.lombardi85@gmail.com>
ip: Cache align ip_stats

- ip_stats is padded to multiple cache line size; add comment about it
- Cache align the per-cpu ip_stats array
kernel/cpu_topology: They are just bits, not BITS.
lnc: Call ether_ifattach() before lance_stop()

So ifnet is properly setup.

While I'm here, remove no longer needed lance_attach() and don't return
error code from lance_config(), which returned no error at all.

DragonFly-bug: http://bugs.dragonflybsd.org/issues/2528
udp: Make stats per-cpu
ipiq: Make stats per-cpu
bce: Try enabling MSI-X on 5716 too

Well, to be frank, I never saw any real "5716" in the field.
bce: Don't use MSI-X, if the effective RX ring count is 1
ipiq: Use cached mycpu to access per-cpu ipiq stats

Reminded-by: sjg@
nrelease: Use variables.