Merge branch 'sb/hook-cleanup'

* sb/hook-cleanup:
  run_hook(): allow more than 9 hook arguments
  run_hook(): check the executability of the hook before filling argv
  api-run-command.txt: talk about run_hook()
  Move run_hook() from builtin-commit.c into run-command.c (libgit)
  checkout: don't crash on file checkout before running post-checkout hook

diff --cc builtin-commit.c
Simple merge