libc - Revert to nmalloc for now

* Disable dmalloc on 64-bit systems, use nmalloc for everything for now.
  dmalloc appears to have some severe fragmentation and/or leak issues
  in long running programs (aka xulrunner) which are worse than nmalloc.
libc - Add poor man's cache coloring optimization to nmalloc module.

* A series of large allocations in excess of 32KB will be offset by 4K from
  each other.  This fixes performance issues on SandyBridge and later cpus
  related to large matrix operations.

  This eats an extra 4K of VM for such allocations but does not eat any
  additional real memory.

* Greatly improves large FP matrix benchmarks.  Real-world effects are more
  questionable.

* The Sandybridge and later cpus use a virtually indexed, physically tagged
  L1 cache, and tend to be sensitive to substantially different memory
  addresses winding up on the same cache line.  Matrix operations (primarily
  benchmarks) can cause these sorts of effects.

Reported-by: alexh
kernel: COMPAT_DF12 is valid for vkernel (32 bit) too.
kernel/posix scheduling: Style, indentation, etc.
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.