Draft: [3.0] contrib: gettext: update to 0.26

It builds properly with gcc 14 mingw-w64.

We only need the runtime part to compile/link with. The native tools are in the system or in extras/tools.

(cherry picked from commit 031aff1c)

Keep as draft until 3.0.22 is tagged. It may have issues with functions not properly detected as missing for macOS 10.7.