vcpkg's vaapi feature builds libva, which needs libdrm headers: the CI
Linux job installs libdrm-dev and the CD debian container did not
(fedora/arch already carry libdrm-devel/libdrm), so its vcpkg install
failed with "You will need to install libdrm dependencies".
Windows has no rsvg-convert either: vcpkg's librsvg port is built with
-Drsvg-convert=disabled, so the icon step now copies the committed
512x512 render (assets/app-icon.png); the Linux icon step falls back to
it too when librsvg2-bin is missing.
Mike-Solar
5fd1c151da