[libxscrnsaver] Update to 1.2.5

[SunBlack]

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

Note:

• meson files are now available for this, but requires the Unix tool sed. The old autoconf script doesn't need it and therefore builds still under Windows.
• Switching to download archive, to avoid SHA issues again with GitLab.

[dg0yt]

• meson files are now available for this, but requires the Unix tool sed. The old autoconf script doesn't need it and therefore builds still under Windows.

Nitpick: sed is available during configure/make which runs in Msys2 bash on Windows. But I don't know if msys2 sed would work well with meson, so not suggesting any action.