SOme ground work to support Windows for benchmark farm

Mainly straightforward changes, the only tricky part: detect number of CPU
sockets. Didn't figure out yet how to do this on Windows.

benchmark/foundation/system_info.py

@@ -69,6 +69,9 @@ def getNumPhysicalCPUs_Linux():
 def getNumPhysicalCPUs():
     if sys.platform == 'linux':
         return getNumPhysicalCPUs_Linux()
+    elif sys.platform == 'win32':
+        # TODO(sergey): Currently all WIndows machines here are single socket.
+        return 1
     else:
         raise Exception("Needs implementation")