review(XS): 7086226: UseNUMA fails on old versions of windows

[Igor Veresov]

 On windows os::numa_get_groups_num() return the wrong answer (0) for machines, where the NUMA API is not supported. Moreover, UseNUMA switches on the NUMA-aware allocator with PS, which doesn't make sense on Windows so far. 

This change fixes the following:
- Turn off UseNUMA on Windows even if it is explicitly specified (ForceNUMA can be used to override that).
- Remove NUMA API initialization warnings if UseNUMA is specified, the convention is to silently ignore that (that's what would happen on other platforms).
- Make os::numa_get_groups_num() return 1 for the case when the API initialization failed. The os::numa_get_leaf_groups() was fixed to behave appropriately too.

Webrev: http://cr.openjdk.java.net/~iveresov/7086226/webrev.00/

Thanks,
igor