Roll libxml2 to 2.14.6

* Update README.chromium to describe patches.
* Change configuration to not build Python integration.
* Adapt 2 patches to fit changed documentation formatting in tree.h.
* Remove some Windows config headers from build description.

https://gitlab.gnome.org/GNOME/libxml2/-/compare/22f9d730898d2dfcc03a484e65e1f8fc3675225f...d23960a130c5bb82779c9405fbbf85e65fb3c57c

Bug: 41442686
Change-Id: I5009224197661350d7309c4dc9a1544bf1cbbe5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7222471
Commit-Queue: Dominik Röttsches <drott@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1553852}
NOKEYCHECK=True
GitOrigin-RevId: 8feb36fd204ec878549002103362d18a1cab3a47
147 files changed