Merge branch 'nd/parseopt-completion-more'

The mechanism to use parse-options API to automate the command line completion continues to get extended and polished. * nd/parseopt-completion-more: completion: use __gitcomp_builtin in _git_cherry completion: use __gitcomp_builtin in _git_ls_tree completion: delete option-only completion commands completion: add --option completion for most builtin commands completion: factor out _git_xxx calling code completion: mention the oldest version we need to support git.c: add hidden option --list-parseopt-builtins git.c: move cmd_struct declaration up