Merge branch 'ar/config-hooks' into ar/config-hook-cleanups

Merge branch 'ar/config-hooks' into ar/config-hook-cleanups

* ar/config-hooks: (21 commits)
  builtin/receive-pack: avoid spinning no-op sideband async threads
  hook: add -z option to "git hook list"
  hook: allow out-of-repo 'git hook' invocations
  hook: allow event = "" to overwrite previous values
  hook: allow disabling config hooks
  hook: include hooks from the config
  hook: add "git hook list" command
  hook: run a list of hooks to prepare for multihook support
  hook: add internal state alloc/free callbacks
  receive-pack: convert receive hooks to hook API
  receive-pack: convert update hooks to new API
  run-command: poll child input in addition to output
  hook: add jobs option
  reference-transaction: use hook API instead of run-command
  transport: convert pre-push to hook API
  hook: allow separate std[out|err] streams
  hook: convert 'post-rewrite' hook in sequencer.c to hook API
  hook: provide stdin via callback
  run-command: add stdin callback for parallelization
  run-command: add helper for pp child states
  ...