fix(build): enable tokio_unstable in build script (#2376)

Co-authored-by: houseme <housemecn@gmail.com>

build-rustfs.sh

@@ -213,7 +213,7 @@ setup_rust_environment() {
     # Set up environment variables for musl targets
     if [[ "$PLATFORM" == *"musl"* ]]; then
         print_message $YELLOW "Setting up environment for musl target..."
-        export RUSTFLAGS="-C target-feature=-crt-static"
+        export RUSTFLAGS="'--cfg tokio_unstable -C target-feature=-crt-static'"
 
         # For cargo-zigbuild, set up additional environment variables
         if command -v cargo-zigbuild &> /dev/null; then
@@ -430,7 +430,7 @@ build_binary() {
         fi
     else
         # Native compilation
-        build_cmd="RUSTFLAGS=-Clink-arg=-lm cargo build"
+        build_cmd="RUSTFLAGS='--cfg tokio_unstable -Clink-arg=-lm' cargo build"
     fi
 
     if [ "$BUILD_TYPE" = "release" ]; then