Fix compile under Windows XP

The needed Windows API for processor groups could be missed from old Windows
versions, so instead of calling them directly (forcing the linker to resolve
the calls at compile time), try to load them at runtime. To do this we need
first to define the corresponding function pointers.

Also don't interfere with running fishtest on numa hardware with Windows.
Avoid all stockfish one-threaded processes will run on the same node

No functional change.