jme: Always save TX interrupt CPUID

This will be used to unify the ifnet.if_cpuid and ifnet.if_npoll_cpuid
igb: Save TX interrupt CPUID into tx_ring struct

This will be used to unify the ifnet.if_cpuid and ifnet.if_npoll_cpuid
kernel/dm: Remove some unused variables.

Also start using a previously unused variable in dm_target_crypt.
kernel/disk: Remove some unused variables and add __debugvar.
kernel: Remove some unused variables in kern/, opencrypto/ and platform/.
kernel/netinet6: Remove some unused variables.
if: Move if_cpuid into ifaltq; prepare multiple TX queues support

if_cpuid and if_npoll_cpuid are merged and moved into ifaltq as
altq_cpuid, which indicates the owner CPU of the tx queue.  Since
we already have code in if_start_dispatch() to catching tx queue
owner CPU changes, this merging is quite safe.
pktgen: Allow pktgenctl to specify # of packets to be queued onto TX queue
if: Move if_start_nmsg into ifaltq; prepare multiple TX queue support

While im here, also rename some functions to be consistent in naming
convention.
Merge branch 'master' into gsocdrm_jfree
kernel -- Import virtio & virtio-block drivers.

virtio-blk provides a paravirtualized storage controller, with one
disk per virtio device.

This driver is based on Tim Bisson's port of FreeBSD's virtio and
virtio-blk devices. Differences from Tim's port:

* Import all FreeBSD updates from 4/16 on.
* Remove indirect descriptor support from virtio device.
* Mark devices as D_MPSAFE; removes mplock around disk routines, they
  are all correctly self-synchronized.
* Implement devstat support.
* Move I/O completion routine to threaded taskqueue.
* Do not hold target spinlock around virtqueue notify.
* Move objcache caches to kmalloc.
Rename vtblk_intr_task to vtblk_complete.
kernel/virtio: Some cleanup (Makefiles and gcc47 warnings).
kernel -- Tie virtio, virtio-blk into build.
Build fixes.
kernel/virtio: Make it compilable into the kernel.

Submitted-by: vsrinivas
Add manual pages for virtio (taken from FreeBSD with modifications).
kernel/hammer: Remove unused variables and add __debugvar.
kernel: Replace the remaining __amd64__ with __x86_64__ for consistency.
kernel/aac: sge64 is only used on x86_64.