Reverted _obj_is_[row|col]_stored() macros.

Details:
- Rolled back recent changes to bli_obj_is_row_stored() and
  bli_obj_is_col_stored() so that those macros now only inspect the
  strides (row or column). It turns out that the more sophisticated
  definitions introduced in a51e32e are not necessary, because these
  "obj" macros are virtually never used on packed matrices, and when
  they are, they can use bli_obj_is_[row|col}_packed() macros, which
  inspect the info bitfield.