TST/COMPAT: numpy master compat with timedelta type coercion
Merge pull request #7681 from jreback/numpy_issue

TST/COMPAT: numpy master compat with timedelta type coercion
TST: skip buggy test on numpy < 1.7, 3.2, on 32-bits (GH6270)
TST: skip buggy test if can't form test comparison (GH7664)