add copy.py

copy.py

+#!/usr/bin/env python3 
+
+import os, sys, shutil
+
+# get absolute input and output paths
+input_path = os.path.join(
+    os.getenv('MESON_SOURCE_ROOT'), 
+    os.getenv('MESON_SUBDIR'),
+    sys.argv[1])
+
+output_path = os.path.join(
+    os.getenv('MESON_BUILD_ROOT'), 
+    os.getenv('MESON_SUBDIR'),
+    sys.argv[2])
+
+# make sure destination directory exists
+os.makedirs(os.path.dirname(output_path), exist_ok=True)
+
+# and finally copy the file
+shutil.copyfile(input_path, output_path)