Fix wasi.py build after adding the clean subcommand. ({GH-114447)

Author: brettcannon

Tools/wasm/wasi.py

@@ -68,7 +68,8 @@ def wrapper(context):
                 terminal_width = 80
             print("⎯" * terminal_width)
             print("📁", working_dir)
-            if clean_ok and context.clean and working_dir.exists():
+            if (clean_ok and getattr(context, "clean", False) and
+                working_dir.exists()):
                 print(f"🚮 Deleting directory (--clean)...")
                 shutil.rmtree(working_dir)