Merge branch 'jn/parse-options-extra' into next

Merge branch 'jn/parse-options-extra' into next

* jn/parse-options-extra:
  update-index: migrate to parse-options API
  setup: save prefix (original cwd relative to toplevel) in startup_info
  parse-options: make resuming easier after PARSE_OPT_STOP_AT_NON_OPTION
  parse-options: allow git commands to invent new option types
  parse-options: never suppress arghelp if LITERAL_ARGHELP is set
  parse-options: do not infer PARSE_OPT_NOARG from option type
  parse-options: sanity check PARSE_OPT_NOARG flag
  parse-options: move NODASH sanity checks to parse_options_check
  parse-options: clearer reporting of API misuse
  parse-options: Don't call parse_options_check() so much