Enable numa interleaving by default when required conditions are met

It would be a good thing to have numa-interleave enabled "automatically" if these conditions are met :

• The server is running with more than one physical CPU on a NUMA architecture without NUMA interleaving enabled on bios
• The server is running on Linux
• The numactl tool is present on the system
• innodb-buffer-pool-size > memory/physicalCPUcount
  (the latter could be optional)

In that case, there would be parameters for --numa-interleave such as true|false|auto to keep it simple if one want to force it either way.

On another hand, throwing a warning in case the interleaving wouldnt be activated but (innodb-buffer-pool-size > memory/physicalCPUcount) and innodb_buffer_pool_instances wouldnt be set (with a value of 1) could be a good thing.