rust: initial merge of most of meta-rust

In the meta-rust repo at commit:
   448047c Upgrade to 1.54.0 (#359)

Make the required directories:
  mkdir ../oe-core/meta/recipes-devtools/rust
  mkdir ../oe-core/meta/recipes-devtools/cargo
  mkdir ../oe-core/meta/recipes-example
and then:
  cp recipes-devtools/rust/* ../oe-core/meta/recipes-devtools/rust
  cp recipes-devtools/cargo/* ../oe-core/meta/recipes-devtools/cargo
  cp lib/crate.py ../oe-core/meta/lib
  cp recipes-example/* ../oe-core/meta/recipes-example
  cp conf/distro/include/rust_* ../oe-core/meta/conf/distro/include/
  cp classes/* ../oe-core/meta/classes/
  cp recipes-core/packagegroups/packagegroup-rust-cross-canadian.bb ../oe-core/meta/recipes-core/packagegroups

(From OE-Core rev: 3ed57578cca93ff1ba4e0bf3f25566e10659a2f9)

Signed-off-by: Randy MacLeod <Randy.MacLeod@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/cargo.bbclass

@@ -0,0 +1,89 @@
+##
+## Purpose:
+## This class is used by any recipes that are built using
+## Cargo.
+
+inherit cargo_common
+
+# the binary we will use
+CARGO = "cargo"
+
+# We need cargo to compile for the target
+BASEDEPENDS:append = " cargo-native"
+
+# Ensure we get the right rust variant
+DEPENDS:append:class-target = " virtual/${TARGET_PREFIX}rust ${RUSTLIB_DEP}"
+DEPENDS:append:class-native = " rust-native"
+
+# Enable build separation
+B = "${WORKDIR}/build"
+
+# In case something fails in the build process, give a bit more feedback on
+# where the issue occured
+export RUST_BACKTRACE = "1"
+
+# The directory of the Cargo.toml relative to the root directory, per default
+# assume there's a Cargo.toml directly in the root directory
+CARGO_SRC_DIR ??= ""
+
+# The actual path to the Cargo.toml
+MANIFEST_PATH ??= "${S}/${CARGO_SRC_DIR}/Cargo.toml"
+
+RUSTFLAGS ??= ""
+BUILD_MODE = "${@['--release', ''][d.getVar('DEBUG_BUILD') == '1']}"
+CARGO_BUILD_FLAGS = "-v --target ${HOST_SYS} ${BUILD_MODE} --manifest-path=${MANIFEST_PATH}"
+
+# This is based on the content of CARGO_BUILD_FLAGS and generally will need to
+# change if CARGO_BUILD_FLAGS changes.
+BUILD_DIR = "${@['release', 'debug'][d.getVar('DEBUG_BUILD') == '1']}"
+CARGO_TARGET_SUBDIR="${HOST_SYS}/${BUILD_DIR}"
+oe_cargo_build () {
+	export RUSTFLAGS="${RUSTFLAGS}"
+	export RUST_TARGET_PATH="${RUST_TARGET_PATH}"
+	bbnote "cargo = $(which ${CARGO})"
+	bbnote "rustc = $(which ${RUSTC})"
+	bbnote "${CARGO} build ${CARGO_BUILD_FLAGS} $@"
+	"${CARGO}" build ${CARGO_BUILD_FLAGS} "$@"
+}
+
+do_compile[progress] = "outof:\s+(\d+)/(\d+)"
+cargo_do_compile () {
+	oe_cargo_fix_env
+	oe_cargo_build
+}
+
+cargo_do_install () {
+	local have_installed=false
+	for tgt in "${B}/target/${CARGO_TARGET_SUBDIR}/"*; do
+		case $tgt in
+		*.so|*.rlib)
+			install -d "${D}${rustlibdir}"
+			install -m755 "$tgt" "${D}${rustlibdir}"
+			have_installed=true
+			;;
+		*examples)
+			if [ -d "$tgt" ]; then
+				for example in "$tgt/"*; do
+					if [ -f "$example" ] && [ -x "$example" ]; then
+						install -d "${D}${bindir}"
+						install -m755 "$example" "${D}${bindir}"
+						have_installed=true
+					fi
+				done
+			fi
+			;;
+		*)
+			if [ -f "$tgt" ] && [ -x "$tgt" ]; then
+				install -d "${D}${bindir}"
+				install -m755 "$tgt" "${D}${bindir}"
+				have_installed=true
+			fi
+			;;
+		esac
+	done
+	if ! $have_installed; then
+		die "Did not find anything to install"
+	fi
+}
+
+EXPORT_FUNCTIONS do_compile do_install