Use the hook API to replace ad-hoc invocation of hook scripts via
the run_command() API.
* ar/run-command-hook-take-2:
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
t1800: add hook output stream tests
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