optionally pass env to AddBuildMiddleware callback (platformio#4380)

Author: bkleiner

platformio/builder/tools/piobuild.py

@@ -292,7 +292,10 @@ def CollectBuildFiles(
  for callback, pattern in middlewares:
  if pattern and not fnmatch.fnmatch(node.srcnode().get_path(), pattern):
  continue
- new_node = callback(new_node)
+ if callback.__code__.co_argcount == 2:
+ new_node = callback(env, new_node)
+ else:
+ new_node = callback(new_node)
  if new_node:
  new_sources.append(new_node)