kernel/acpi: Use device_printf() in a few places.
kernel: make pktinfo and cpuid native to ip_input()

In order to remove ether_input_pkt(), switch the prototype
of if_input() and adjust all callers.  While there, consolidate
the style of the invoke.

Suggested and reviewed by: sephe
kernel: switch newer drivers back to if_input()

Restore the if_input() invoke.  This is needed to reenable
tapping into if_input through drivers like netmap(4).

Reviewed by: sephe
kernel - Fix several taskqueue livelocks

* Taskqueue was trying to issue callout_*() operations with a spin-lock
  held on callouts associated with other cpus.  This can livelock the
  system.

* Unlock the taskqueue spinlock when messing with callout_*() operations.

* Fixes an indefinite spin lock panic from drm/ttm.
dmesg - Add -ff feature

* Add a feature whereby if -f is specified twice (-ff), dmesg will
  not sleep() in its monitoring loop and will instead live loop.
  This feature is intended only to help debug crashing kernel situations
  and should not be used for normal dmesg monitoring.
kernel - add vm_contig_avail_pages() API

* Add a function which DRM can query to determine how much more-easily-DMAd
  memory is available from our contiguous memmory pool, instead of assuming
  that it can gobble all 4GB of 'low' memory before it tries to swap.

* This memory is typically set in /boot/loader.conf, like this:

  vm.dma_reserved=256m

  The default is ~16MB at the moment so users will generally want to increase
  it.