Simplify and fix anvil recipe

Also share sources between smallvil and anvil recipes.

recipes/wip/wayland/anvil/recipe.toml

@@ -1,21 +1,14 @@
 #TODO not compiled or tested
 [source]
-git = "https://github.com/Smithay/smithay"
+same_as = "../smallvil"
+
 [build]
+template = "cargo"
 dependencies = [
+    "libffi",
     "libwayland",
     "libxkbcommon",
 ]
-template = "custom"
-script = """
-package=anvil
-"${COOKBOOK_CARGO}" build \
-            --manifest-path "${COOKBOOK_SOURCE}/Cargo.toml" \
-            --package "${package}" \
-            --release
-            --winit
-        mkdir -pv "${COOKBOOK_STAGE}/usr/bin"
-        cp -v \
-            "target/${TARGET}/release/${package}" \
-            "${COOKBOOK_STAGE}/usr/bin/${package}"
-"""
+cargopackages = [
+    "anvil"
+]