'RELENG_7_0_0_RELEASE'.

This commit was manufactured to restore the state of the 7.0-RELEASE image.

MFC after:	3 days

but then sizes the containing data structure at run-time to make room
for per-cpu cache data.  Modify libmemstat to separately allocate a
buffer to hold per-cpu cache data, sized based on the run-time mp_maxid
variable when using libkvm to access UMA data.  This avoids reading
invalid cache data from beyond the end of the uma_zone data structure
on the stack, which can result in invalid statistics and/or reads from
invalid kernel addresses.

Foot target practice by:	ps
MFC after:			3 days

return a KVM error rather than an out of memory error, so that the caller
reports the KVM error state.  This replaces a misleading error message
with a more accurate although equally confusing one.

MFC after:	3 days

cpu mask before looking at the cache entries for the CPU.  For systems
with sparse CPU id arrays, this skips otherwise uninitialized cache
structures.

MFC after:	3 days

bytes = allocated - freed, not bytes = allocated = freed.

MFC after:	3 days

list, which could cause problems for multi-threaded applications
using libmemstat to monitor UMA in more than one thread
simultaneously.

MFC after:	3 days

opt_vmpage.h.

Remove definition of _KERNEL, it is no longer required in order to
include uma_int.h, as the sensitive parts of uma_int.h (a number of
inlines depending on kernel-only constants) are now protected by
_KERNEL.

that knows how to extract UMA(9) allocator statistics from a core dump or
live memory image using kvm(3).  The caller is expected to provide the
necessary kvm_t handle, which is then used by libmemstat(3).

With these changes, it is trivially straight forward to re-introduce
vmstat -z support on core dumps, which was lost when UMA was introduced.

In the short term, this requires including vm/ include files that are not
intended for extra-kernel use, requiring in turn some ugliness.

- Move memory_type_list flushing logic from memstat_mtl_free() to
  _memstat_mtl_empty(), a libmemstat-internal function that can
  be called from other parts of the library.  Invoke
  _memstat_mtl_empty() from memstat_mtl_free(), which also frees
  the containing list structure.

  Invoke _memstat_mtl_empty() instead of memstat_mtl_free() in
  various error cases in memstat_malloc.c and memstat_uma.c, which
  previously resulted in the list being freed prematurely.

- Reverse the order of updating the mt_kegfree and mt_free fields
  of the memory_type in memstat_uma.c, otherwise keg free items
  won't be counted properly for non-secondary zones.

MFC after:	3 days