Rewrite of the "git bisect" script in C continues.
* mr/bisect-in-c-2:
bisect--helper: reimplement `bisect_next` and `bisect_auto_next` shell functions in C
bisect: call 'clear_commit_marks_all()' in 'bisect_next_all()'
bisect--helper: reimplement `bisect_autostart` shell function in C
bisect--helper: introduce new `write_in_file()` function
bisect--helper: use '-res' in 'cmd_bisect__helper' return
bisect--helper: BUG() in cmd_*() on invalid subcommand