DOC: Update the docs for the C API to reflect the change in return type of PyArray_ITEMSIZE
MAINT: Update printf statements in fortranobject.c

Using NPY_INTP_FMT to format PyArray_ITEMSIZE
MAINT: cast PyArray_ITEMSIZE result to avoid warnings

return type depends on API version used
Merge pull request #5287 from chatcannon/reconcile-c-api-with-docs

Reconcile C API with docs