ecore ecore_x_e: check 0 and -1 for ecore_x_window_prop_card32_get() return value...

ecore ecore_x_e: check 0 and -1 for ecore_x_window_prop_card32_get() return value which mean fail.

- ecore_x_window_prop_card32_get() returns:
  -1 if the property was not successfully fetched.
  0 if the property exists but has no elements.