Fix Debian cross-linking with xx-cargo (#7524)

* Fix Debian cross-linking with xx-cargo

* Fix SC2155 in Debian cross builds

docker/Dockerfile.j2

@@ -28,8 +28,13 @@
 #     [docker.io/vaultwarden/web-vault:{{ vault_version | replace('+', '_') }}]
 #
 {% macro xx_cargo_config() -%}
-# Workaround for xx related build issues
+# Configure xx-cargo for target pkg-config and Debian transitive library lookup
     # https://github.com/tonistiigi/xx/pull/108#issuecomment-3700635977
+    # https://github.com/dani-garcia/vaultwarden/discussions/7522
+    if xx-info is-cross; then \
+        XX_RUSTFLAGS="-C link-arg=-Wl,-rpath-link,/usr/lib/$(xx-info triple)"; \
+        export XX_RUSTFLAGS; \
+    fi && \
     PKG_CONFIG="$(command -v "$(xx-info)-pkg-config")" xx-cargo build --features ${DB} --profile "${CARGO_PROFILE}"
 {%- endmacro %}
 FROM --platform=linux/amd64 docker.io/vaultwarden/web-vault@{{ vault_image_digest }} AS vault