(meson-)winbuild.sh: Check that crosser setup is supported
winbuild.sh and meson-winbuild.sh should check that crosser setup one we support. We currently support them all, but crosser might soon have some new ones.
winbuild.sh and meson-winbuild.sh should check that crosser setup one we support. We currently support them all, but crosser might soon have some new ones.