gh-122044: Don't error during gitignore filtering with no files (#122045

)

Tools/build/generate_sbom.py

@@ -108,6 +108,10 @@ def filter_gitignored_paths(paths: list[str]) -> list[str]:
 
  '.gitignore:9:*.a Tools/lib.a'
  """
+ # No paths means no filtering to be done.
+ if not paths:
+ return []
+
  # Filter out files in gitignore.
  # Non-matching files show up as '::<whitespace><path>'
  git_check_ignore_proc = subprocess.run(