This patch fixes the following build breakage which happens when CONFIG_NUMA is
enabled but CONFIG_SMP is disabled:

    CC      mm/slqb.o
  mm/slqb.c: In function '__slab_free':
  mm/slqb.c:1735: error: implicit declaration of function 'slab_free_to_remote'
  mm/slqb.c: In function 'kmem_cache_open':
  mm/slqb.c:2274: error: implicit declaration of function 'kmem_cache_dyn_array_free'
  mm/slqb.c:2275: warning: label 'error_cpu_array' defined but not used
  mm/slqb.c: In function 'kmem_cache_destroy':
  mm/slqb.c:2395: error: implicit declaration of function 'claim_remote_free_list'
  mm/slqb.c: In function 'kmem_cache_init':
  mm/slqb.c:2885: error: 'per_cpu__kmem_cpu_nodes' undeclared (first use in this function)
  mm/slqb.c:2885: error: (Each undeclared identifier is reported only once
  mm/slqb.c:2885: error: for each function it appears in.)
  mm/slqb.c:2886: error: 'kmem_cpu_cache' undeclared (first use in this function)
  make[1]: *** [mm/slqb.o] Error 1
  make: *** [mm] Error 2

As x86 Kconfig doesn't even allow this combination, one is tempted to
think it's an architecture Kconfig bug. But as it turns out, it's a
perfecly valid configuration. Tony Luck explains:

  UP + NUMA is a special case of memory-only nodes.  There are some (crazy?)
  customers with problems that require very large amounts of memory, but not very
  much cpu horse power.  They buy large multi-node systems and populate all the
  nodes with as much memory as they can afford, but most nodes get zero cpus.

So lets fix that up.

[ tony.luck@intel.com: #ifdef cleanups ]
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>