Merge branch 'jk/fast-export-cleanup'

Code clean-up.

* jk/fast-export-cleanup:
  fast-export: drop unused parameter from anonymize_commit_message()
  fast-export: drop data parameter from anonymous generators
  fast-export: de-obfuscate --anonymize-map handling
  fast-export: factor out anonymized_entry creation
  fast-export: simplify initialization of anonymized hashmaps
  fast-export: drop const when storing anonymized values