TST: win32 fixes

TST: test_indexing dtype comps, closes #5466

TST don't compare invalid indices in eval operations, closes #5467

TST: invalid assignment for np.timedelta64 closes #5465

TST: skip locale checks on windows cloes #5464

TST: dtype comp issue on windows in test_indexing (GH5466)

TST: skip test_pow on windows (GH5467)