FIX: Include file name in error message.

Real helpful for actually fixing the thing.

tools/check_python_h_first.py

@@ -87,7 +87,10 @@ def check_python_h_included_first(name_to_check: str) -> int:
  included_non_python_headers.append(i)
 
  if this_header in included_headers:
- print(f"Header {this_header:s} included twice, second on line {i:d}", file=sys.stderr)
+ print(
+ f"Header {this_header:s} included twice in file {name_to_check:s}, second on line {i:d}",
+ file=sys.stderr
+ )
  duplicate_header_count += 1
  included_headers.append(this_header)
  elif (not included_python and not warned_python_construct and ".h" not in basename_to_check) and (