package/pkg-cargo.mk: introduce the cargo package infrastructure

In order to be package agnostic, the install phase is now using cargo
instead of install. TARGET_CONFIGURE_OPTS is now also set when running
cargo in order to support cross compiling C code within cargo.

This commit also adds support/download/cargo-post-process to perform
the vendoring on Cargo packages.

The <pkg>_LICENSE variable of cargo packages is expanded with ",
vendored dependencies licenses probably not listed" as currently for
all packages, the licenses of the vendored dependencies are not taken
into account.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
[Thomas: add support for host-cargo-package and vendoring]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

support/download/cargo-post-process

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+set -e
+
+. "${0%/*}/helpers"
+
+while getopts "n:o:" OPT; do
+    case "${OPT}" in
+    o)  output="${OPTARG}";;
+    n)  base_name="${OPTARG}";;
+    :)  error "option '%s' expects a mandatory argument\n" "${OPTARG}";;
+    \?) error "unknown option '%s'\n" "${OPTARG}";;
+    esac
+done
+
+# Already vendored tarball, nothing to do
+if tar tf "${output}" | grep -q "^[^/]*/VENDOR" ; then
+    exit 0
+fi
+
+post_process_unpack "${base_name}" "${output}"
+
+# Do the Cargo vendoring
+pushd "${base_name}" > /dev/null
+cargo vendor --locked VENDOR
+
+# Create the local .cargo/config with vendor info
+mkdir -p .cargo/
+cat <<EOF >.cargo/config
+[source.crates-io]
+replace-with = "vendored-sources"
+
+[source.vendored-sources]
+directory = "VENDOR"
+EOF
+popd > /dev/null
+
+post_process_repack "$(pwd)" "${base_name}" "${output}"