main/gettext: upgrade to 0.24

When building version 0.22.5, the msgmerge-28 and msgmerge-compendium-5 tests fail, and the upstream has already merged the musl-realpath.patch. https://savannah.gnu.org/news/?id=10730

gettext 0.22 has test failures when built against libunistrings 1.3 as acknowledged by upstream. This has been fixed in 0.23.

libxml2 was upgraded to 2.14, but later reverted again because it introduced a bunch of breakages against various packages, one of which is gettext. Add a version constraint to make sure the builder picks op 2.13 instead of 2.14.

Fixes #17035 (closed)