UBUNTU: SAUCE: Documentation: import error c_funcptr_sig_re, c_sig_re (sphinx-doc...

UBUNTU: SAUCE: Documentation: import error c_funcptr_sig_re, c_sig_re (sphinx-doc/sphinx@0f49e30c)

Extension error:
   Could not import extension linuxdoc.cdomain  .. \
   (exception: cannot import name 'c_funcptr_sig_re' from ..

Issue: `sphinx-doc/sphinx#7421`_

.. _0f49e30c:
   https://github.com/sphinx-doc/sphinx/commit/0f49e30c51b5cc5055cda5b4b294c2dd9d1df573#r38750737

.. _sphinx-doc/sphinx#7421:
   https://github.com/sphinx-doc/sphinx/issues/7421

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Link: https://github.com/return42/linuxdoc/commit/48f09de2aff80169b7b9be5b0f2431ad8954e5cc
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>