wmi: Makes _get_method_params thread safe
wmi: Makes _get_method_params thread safe

_get_method_params is supposed to return a unique Object
in which a method's parameters are mapped. The issue is that
it always returns the same object, which can be modified by
multiple threads, leading to erroneous method calls.

Method now returns a cloned object.

cloudbase/PyMI,alinbalutoiu/PyMI,alinbalutoiu/PyMI,cloudbase/PyMI,cloudbase/PyMI,alinbalutoiu/PyMI