Merge branch 'ps/leakfixes-part-7'

Merge branch 'ps/leakfixes-part-7'

More leak-fixes.

* ps/leakfixes-part-7: (23 commits)
  diffcore-break: fix leaking filespecs when merging broken pairs
  revision: fix leaking parents when simplifying commits
  builtin/maintenance: fix leak in `get_schedule_cmd()`
  builtin/maintenance: fix leaking config string
  promisor-remote: fix leaking partial clone filter
  grep: fix leaking grep pattern
  submodule: fix leaking submodule ODB paths
  trace2: destroy context stored in thread-local storage
  builtin/difftool: plug several trivial memory leaks
  builtin/repack: fix leaking configuration
  diffcore-order: fix leaking buffer when parsing orderfiles
  parse-options: free previous value of `OPTION_FILENAME`
  diff: fix leaking orderfile option
  builtin/pull: fix leaking "ff" option
  dir: fix off by one errors for ignored and untracked entries
  builtin/submodule--helper: fix leaking remote ref on errors
  t/helper: fix leaking subrepo in nested submodule config helper
  builtin/submodule--helper: fix leaking error buffer
  builtin/submodule--helper: clear child process when not running it
  submodule: fix leaking update strategy
  ...