Bugfix: pass struct size as itemsize to descriptor
Without this, partially bound structs will have incorrect itemsize.
diff --git a/include/pybind11/numpy.h b/include/pybind11/numpy.h
index 1046cd4..423403d 100644
--- a/include/pybind11/numpy.h
+++ b/include/pybind11/numpy.h
@@ -266,6 +266,7 @@
args["names"] = names;
args["offsets"] = offsets;
args["formats"] = formats;
+ args["itemsize"] = int_(sizeof(T));
// This is essentially the same as calling np.dtype() constructor in Python and passing
// it a dict of the form {'names': ..., 'formats': ..., 'offsets': ...}.
if (!api.PyArray_DescrConverter_(args.release().ptr(), &dtype_()) || !dtype_())