LaTeX: extra vertical whitespace for some nested declarations

[jfbu]

Describe the bug

Extra vertical whitespace in pdf output:

How to Reproduce

            -msse
            -msse2

   .. note::

      A note in the option description

.. c:function:: PyObject *PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)

   .. note::

      Extra vertical space also in this case if note is first item

.. cpp:class:: Data

   .. cpp:union:: @data

      .. cpp:var:: int a

      .. cpp:var:: double b

Explicit ref: :cpp:var:Data::@data::a. Short-hand ref: :cpp:var:Data::a.

Additional context

Relates #9926

(I edited this as the output from the new issue template is not very useful, and input was a bit painful too)