Merge branch 'rs/run-command-env-array'

Add managed "env" array to child_process to clarify the lifetime
rules.

* rs/run-command-env-array:
  use env_array member of struct child_process
  run-command: add env_array, an optional argv_array for env

diff --cc builtin/receive-pack.c
Simple merge

diff --cc http-backend.c
Simple merge

diff --cc transport-helper.c
Simple merge

diff --cc wt-status.c
Simple merge