Ruby

merge revision(s) d6a2bce64a7fa1099e507e1d36b5f1533f42f60f,c687be4bc01c9ce52ea990945d9304d6fe59fe9b: [Backport #16159]

    time.c (find_time_t): fix round-to-zero bug

    `find_time_t` did not work correctly for year older than the Epoch
    because it used C's integer division (which rounds negative to zero).

    For example, `TIme.new(1933)` returned a wrong time whose year is 1922
    in Asia/Kuala_Lumpur because there is no 00:00:00 1st Jan. 1933 in the
    time zone.

    ```
    $ TZ=Asia/Kuala_Lumpur ruby -e 'p Time.new(1933)'
    1932-12-31 00:00:00 +0700
    ```

    This change fixes the issue by using `DIV` macro instead of `/`.
    Now `Time.new(1933)` returns a time in 1933.

    ```
    $ TZ=Asia/Kuala_Lumpur ruby -e 'p Time.new(1933)'
    1933-01-01 00:20:00 +0720
    ```

    [Bug #16159]

    Added a test for [Bug #16159]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67836 b2dd03c8-39d4-4d8f-98ff-823fe69b080e