Merge branch 'ps/leakfixes-part-4'

Merge branch 'ps/leakfixes-part-4'

More leak fixes.

* ps/leakfixes-part-4: (22 commits)
  builtin/diff: free symmetric diff members
  diff: free state populated via options
  builtin/log: fix leak when showing converted blob contents
  userdiff: fix leaking memory for configured diff drivers
  builtin/format-patch: fix various trivial memory leaks
  diff: fix leak when parsing invalid ignore regex option
  unpack-trees: clear index when not propagating it
  sequencer: release todo list on error paths
  merge-ort: unconditionally release attributes index
  builtin/fast-export: plug leaking tag names
  builtin/fast-export: fix leaking diff options
  builtin/fast-import: plug trivial memory leaks
  builtin/notes: fix leaking `struct notes_tree` when merging notes
  builtin/rebase: fix leaking `commit.gpgsign` value
  config: fix leaking comment character config
  submodule-config: fix leaking name entry when traversing submodules
  read-cache: fix leaking hashfile when writing index fails
  bulk-checkin: fix leaking state TODO
  object-name: fix leaking symlink paths in object context
  object-file: fix memory leak when reading corrupted headers
  ...