Update Rust program build script paths (#4707)

sdk/bpf/rust/build.sh

@@ -9,9 +9,9 @@ if [ ! -f "$1/Cargo.toml" ]; then
     exit 1
 fi
 
-cd "$(dirname "$0")"
+pushd "$(dirname "$0")"
 bpf_sdk="$PWD/.."
-export XARGO_HOME="$PWD/../../../target/xargo"
+popd
 
 cd "$1"
 
@@ -37,6 +37,7 @@ export RUSTFLAGS="
     -C link-arg=-shared \
     -C link-arg=--entry=entrypoint \
     -C linker=$bpf_sdk/dependencies/llvm-native/bin/ld.lld"
+export XARGO_HOME="$bpf_sdk/dependencies/xargo"
 export XARGO_RUST_SRC="$bpf_sdk/dependencies/rust-bpf-sysroot/src"
 xargo build --target bpfel-unknown-unknown --release -v