Msys2 Makefile.meson: No freeciv-mp-gtk4.cmd link in sdl2-client installer
More accurately: We build gtk3-fcmp, but the script generating sdl2-client .nsi script has gtk4-fcmp hardcoded to it.
We could make create-sdl2-....nsi to take fcmp gui as a parameter, like create-gtk-qt-...nsi does (since it needs to support both gtk, and qt fcmp), but that's not a very high priority. We should be updating Makefile.meson towards gtk4 usage anyway.
Modpack installer cannot be launched for meson built msys2 sdl2-client installer, as the link is missing.