The lack of this check led to a segfault.

Closes #4613.

Set the `NPY_NEEDS_PYAPI` flag for types with fields, as these need
access to the Python API to manipulate the tuples and dicts holding
field information. It remains unset for the base `np.void` type.

closes gh-4774

e.g. doubles are only aligned to 4 bytes on i386 so one cannot peel them
to 16 byte alignment.
Closes gh-4853

when orders are selected where the kth element falls into an equal range
the the last stored pivot was not the kth element, this leads to losing
the ordering of smaller orders as following selection steps can start at
index 0 again instead of the at the offset of the last selection.
Closes gh-4836

existing test is very slow and eats all the RAM of my testing VM,
windows apparently does not have sparse memory.

fixes the test on windows where mingw _mktemp64 will return an error
instead of a negative time.

The FirstVisit function uses this, but when the reduction is
over a single element it isn't considered a reduction. This is
fine, however the reduce pos must still be initialized to 0 in
that case. Also changes the check order so that it is not
necessary to initialize the outerstrides as well.

See also gh-4134, and gh-4535.