[Outreachy] [PATCH v4 00/12] Finish converting git bisect to C part 1

These patches correspond to a first part of patch series of Outreachy project "Finish converting `git bisect` from shell to C" started by Pranit Bauva and Tanushree Tumane (https://public-inbox.org/git/pull.117.git.gitgitgadget@gmail.com) and continued by me.

This first part is formed of preparatory/clean-up patches and all `bisect.c` libification work.

I would like to thank René Scharfe and Taylor Blau for their suggestions.

These patch series emails were generated from: https://gitlab.com/mirucam/git/commits/git-bisect-work-part1-v4

--- Changes since v3 Finish converting git bisect to C part 1 patch series ---

General changes ---------------

* Removed `run-command: make exists_in_PATH() non-static` patch of this
part 1 patch series.

Miriam Rubio (3):
  bisect--helper: convert `vocab_*` char pointers to char arrays
  bisect: use the standard 'if (!var)' way to check for 0
  bisect: add enum to represent bisect returning codes

Pranit Bauva (7):
  bisect--helper: return error codes from `cmd_bisect__helper()`
  bisect: libify `exit_if_skipped_commits` to `error_if_skipped*` and
    its dependents
  bisect: libify `bisect_checkout`
  bisect: libify `check_merge_bases` and its dependents
  bisect: libify `check_good_are_ancestors_of_bad` and its dependents
  bisect: libify `handle_bad_merge_base` and its dependents
  bisect: libify `bisect_next_all`

Tanushree Tumane (2):
  bisect--helper: change `retval` to `res`
  bisect--helper: introduce new `decide_next()` function

 bisect.c                 | 135 +++++++++++++++++++++++++++------------
 bisect.h                 |  29 ++++++++-
 builtin/bisect--helper.c | 123 +++++++++++++++++++----------------
 3 files changed, 189 insertions(+), 98 deletions(-)