Update kernel recipe for new initfs format

recipes/kernel/init.rc

-export PATH /bin
-export TMPDIR /tmp
-nulld
-zerod
-randd
-vesad T T G
-logd debug: display:1
-stdio log:
-ps2d us
-ramfs logging
-acpid
-pcid /etc/pcid/initfs.toml
-redoxfs --uuid $REDOXFS_UUID file $REDOXFS_BLOCK
-cd file:
-export PATH file:/bin
-run.d /etc/init.d

recipes/kernel/recipe.sh

-GIT=https://gitlab.redox-os.org/redox-os/kernel.git
-BUILD_DEPENDS=(
-	drivers
-	init
-	logd
-	nulld
-	ramfs
-	randd
-	redoxfs
-	zerod
-)
-
-function recipe_build {
-    export INITFS_FOLDER="$(realpath ../sysroot)"
-    mkdir -pv "$INITFS_FOLDER/etc"
-    cp -v "$(realpath ../init.rc)" "$INITFS_FOLDER/etc/init.rc"
-    cargo rustc \
-        --lib \
-        --target "${ARCH}-unknown-kernel" \
-        --release \
-		-Z build-std=core,alloc \
-        -- \
-        -C soft-float \
-        -C debuginfo=2 \
-		-C lto \
-        --emit link=libkernel.a
-    ../kernel_ld.sh "${LD}" \
-        --gc-sections \
-        -z max-page-size=0x1000 \
-        -T "linkers/${ARCH}.ld" \
-        -o kernel \
-        libkernel.a
-    "${OBJCOPY}" \
-        --only-keep-debug \
-        kernel \
-        kernel.sym
-    "${OBJCOPY}" \
-        --strip-debug \
-        kernel
-    skip=1
-}
-
-function recipe_test {
-    echo "skipping test"
-    skip=1
-}
-
-function recipe_clean {
-    "$REDOX_MAKE" clean
-    skip=1
-}
-
-function recipe_stage {
-    dest="$(realpath $1)"
-    cp -v kernel "$dest"
-    skip=1
-}

recipes/kernel/recipe.toml

+[source]
+git = "https://gitlab.redox-os.org/redox-os/kernel.git"
+
+[build]
+template = "custom"
+script = """
+export RUST_TARGET_PATH="${COOKBOOK_SOURCE}/targets"
+ARCH="$(echo "${TARGET}" | cut -d - -f1)"
+cargo rustc \
+	--lib \
+	--manifest-path "${COOKBOOK_SOURCE}/Cargo.toml" \
+	--target "${COOKBOOK_SOURCE}/targets/${ARCH}-unknown-kernel.json" \
+	--release \
+	-Z build-std=core,alloc \
+	-- \
+	-C soft-float \
+	-C debuginfo=2 \
+	-C lto \
+	--emit link="${PWD}/libkernel.a"
+"${COOKBOOK_RECIPE}/kernel_ld.sh" "${TARGET}-ld" \
+	--gc-sections \
+	-z max-page-size=0x1000 \
+	-T "${COOKBOOK_SOURCE}/linkers/${ARCH}.ld" \
+	-o kernel.all \
+	libkernel.a
+"${TARGET}-objcopy" \
+	--only-keep-debug \
+	kernel.all \
+	kernel.sym
+"${TARGET}-objcopy" \
+	--strip-debug \
+	kernel.all \
+	kernel
+cp -v kernel "${COOKBOOK_STAGE}"
+"""