rust: switch to using _class-cross and _class-native variables to stop abusing the BBCLASSEXTEND system

classes/internal-rust-cross.bbclass

@@ -1,29 +0,0 @@
-inherit cross
-
-# Otherwise we'll depend on what we provide
-INHIBIT_DEFAULT_RUST_DEPS = "1"
-DEPENDS += "rust-native"
-PROVIDES = "virtual/${TARGET_PREFIX}rust"
-PN = "rust-cross-${TARGET_ARCH}"
-
-# The same value as ${TOOLCHAIN_OPTIONS}. We can't use that variable directly
-# here because cross.bblcass is "helpful" and blanks it out.
-#TARGET_PRE_LINK_ARGS_append = " --sysroot=${STAGING_DIR_TARGET}"
-
-# FIXME: the only way to convince cargo to include the rpath is via editing
-# Config.toml, and doing that safely requires us to write actual patches
-HOST_PRE_LINK_ARGS_append = " -Wl,-rpath=${libdir}"
-BUILD_PRE_LINK_ARGS_append = " -Wl,-rpath=${libdir}"
-
-# We need the same thing for the calls to the compiler when building the runtime crap
-TARGET_CC_ARCH_append = " --sysroot=${STAGING_DIR_TARGET}"
-
-## gcc-cross settings
-# INHIBIT_DEFAULT_DEPS = "1"
-# INHIBIT_PACKAGE_STRIP = "1"
-# ARCH_FLAGS_FOR_TARGET += "-isystem${STAGING_DIR_NATIVE}${target_includedir}"
-
-# cross.bbclass is "helpful" and overrides our do_install. Tell it not to.
-do_install () {
-	rust_do_install
-}

classes/internal-rust-native.bbclass

@@ -1,10 +0,0 @@
-inherit native
-PN = "rust-native"
-
-# Otherwise we'll depend on what we provide
-INHIBIT_DEFAULT_RUST_DEPS = "1"
-# We don't need to depend on gcc-native because yocto assumes it exists
-PROVIDES = "virtual/${TARGET_PREFIX}rust"
-
-USE_LOCAL_NATIVE_RUST ??= "0"
-USE_LOCAL_RUST ?= "${@base_conditional('USE_LOCAL_NATIVE_RUST', '0', '0', '1', d)}"