install rustup targets for MacOS and Windows

Some of the rust-vmm crates (such as vmm-sys-util and vm-memory) have
somewhat rudimentary support for MacOS and Windows. While our CI does
not have the means to test these platforms (the rust-vmm CI runners are
linux-only), it can at least do some simple compile testing using `cargo
check` (as long as we do not have any build dependencies that try to
compile native libraries). For this, install the required cargo targets
into the docker container, such that crates that wish to do such compile
testing can specify such additional tests in their custom tests
pipelines.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

build_container.sh

@@ -77,6 +77,12 @@ if [ "$ARCH" != "riscv64" ]; then
     rustup target add $ARCH-unknown-linux-musl $ARCH-unknown-none
 fi
 
+# The below are only used for compile-testing via cargo check.
+# It suffices to do that on _one_ architecture.
+if [ "$ARCH" == "x86_64" ]; then
+    rustup target add aarch64-apple-darwin x86_64-pc-windows-gnu
+fi
+
 cargo install cargo-llvm-cov
 
 # Install the codecov.io uploader. Not available on riscv64, so skip there