fix spurious make error

Makefile

@@ -173,7 +173,7 @@ build/v86.wasm: $(RUST_FILES) build/softfloat.o build/zstddeclib.o Cargo.toml
 	mkdir -p build/
 	-BLOCK_SIZE=K ls -l build/v86.wasm
 	cargo rustc --release $(CARGO_FLAGS)
-	mv build/wasm32-unknown-unknown/release/v86.wasm build/v86.wasm
+	cp build/wasm32-unknown-unknown/release/v86.wasm build/v86.wasm
 	-$(WASM_OPT) && wasm-opt -O2 --strip-debug build/v86.wasm -o build/v86.wasm
 	BLOCK_SIZE=K ls -l build/v86.wasm
 
@@ -181,23 +181,23 @@ build/v86-debug.wasm: $(RUST_FILES) build/softfloat.o build/zstddeclib.o Cargo.t
 	mkdir -p build/
 	-BLOCK_SIZE=K ls -l build/v86-debug.wasm
 	cargo rustc $(CARGO_FLAGS)
-	mv build/wasm32-unknown-unknown/debug/v86.wasm build/v86-debug.wasm
+	cp build/wasm32-unknown-unknown/debug/v86.wasm build/v86-debug.wasm
 	BLOCK_SIZE=K ls -l build/v86-debug.wasm
 
 build/v86-fallback.wasm: $(RUST_FILES) build/softfloat.o build/zstddeclib.o Cargo.toml
 	mkdir -p build/
 	cargo rustc --release $(CARGO_FLAGS_SAFE)
-	mv build/wasm32-unknown-unknown/release/v86.wasm build/v86-fallback.wasm || true
+	cp build/wasm32-unknown-unknown/release/v86.wasm build/v86-fallback.wasm || true
 
 debug-with-profiler: $(RUST_FILES) build/softfloat.o build/zstddeclib.o Cargo.toml
 	mkdir -p build/
 	cargo rustc --features profiler $(CARGO_FLAGS)
-	mv build/wasm32-unknown-unknown/debug/v86.wasm build/v86-debug.wasm || true
+	cp build/wasm32-unknown-unknown/debug/v86.wasm build/v86-debug.wasm || true
 
 with-profiler: $(RUST_FILES) build/softfloat.o build/zstddeclib.o Cargo.toml
 	mkdir -p build/
 	cargo rustc --release --features profiler $(CARGO_FLAGS)
-	mv build/wasm32-unknown-unknown/release/v86.wasm build/v86.wasm || true
+	cp build/wasm32-unknown-unknown/release/v86.wasm build/v86.wasm || true
 
 build/softfloat.o: lib/softfloat/softfloat.c
 	mkdir -p build