Manually install rustup when building debian VM am: 198a0fb573 am: b7cb80fcf3

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/3290127

Change-Id: I51e9d3e073de61f3522b83382dc5d818559af53d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/build/debian/build.sh b/build/debian/build.sh
index eff59a0..5894eaf 100755
--- a/build/debian/build.sh
+++ b/build/debian/build.sh
@@ -38,13 +38,16 @@
 	DEBIAN_FRONTEND=noninteractive \
 	apt install --no-install-recommends --assume-yes \
 		binfmt-support \
+		build-essential \
 		ca-certificates \
+		curl \
 		debsums \
 		dosfstools \
 		fai-server \
 		fai-setup-storage \
 		fdisk \
 		gcc-aarch64-linux-gnu \
+		libc6-dev-arm64-cross \
 		make \
 		python3 \
 		python3-libcloud \
@@ -57,11 +60,12 @@
 		udev \
 
 
-	which cargo > /dev/null 2>&1 || {
-		apt install --no-install-recommends --assume-yes rustup
-		rustup default stable
-		rustup update
-	}
+	if [ ! -f $HOME/.cargo/bin/cargo ]; then
+		curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+	fi
+
+        source $HOME/.cargo/env
+        rustup target add aarch64-unknown-linux-gnu
 
         sed -i s/losetup\ -f/losetup\ -P\ -f/g /usr/sbin/fai-diskimage
         sed -i 's/wget \$/wget -t 0 \$/g' /usr/share/debootstrap/functions
@@ -96,7 +100,7 @@
 	wget ${url} -O ${dst}/files/usr/local/bin/ttyd/AVF
 	chmod 777 ${dst}/files/usr/local/bin/ttyd/AVF
 
-	pushd forwarder_guest > /dev/null
+        pushd $(dirname $0)/forwarder_guest > /dev/null
 		RUSTFLAGS="-C linker=aarch64-linux-gnu-gcc" cargo build \
 			--target aarch64-unknown-linux-gnu \
 			--target-dir ${workdir}/forwarder_guest