Gating network behind compile flag

tools/writeifchanged.py

@@ -0,0 +1,13 @@
+import os
+
+def write_if_changed(path, content):
+  try:
+    with open(path, "r", encoding="utf-8") as f:
+      if f.read() == content:
+        return
+  except FileNotFoundError:
+    pass
+
+  os.makedirs(os.path.dirname(path), exist_ok=True)
+  with open(path, "w", encoding="utf-8") as f:
+    f.write(content)