graphics/inkscape: Fix build with libxml2 2.13 and import backports in tree

Backport upstream patch:
6bbd3647c4d6aab425e53cb4b7d3f33a98e45e6f

While at it also keep previous backport locally in tree to avoid
metadata changes

Reference:
https://gitlab.com/inkscape/inkscape/-/commit/6bbd3647c4d6aab425e53cb4b7d3f33a98e45e6f

PR: 280162
Approved by: portmgr (maintainer timeout, 2+ weeks)