Changes file for the 32-bit msec conversion fixes of #27139

  o Minor bugfixes (32-bit OSX and iOS, timing):

    - Fix an integer overflow bug in our optimized 32-bit millisecond-

      difference algorithm for 32-bit Apple platforms. Previously, it

      would overflow when calculating the difference between two times

      more than 47 days apart.  Fixes part of bug 27139; bugfix on

      0.3.4.1-alpha.

    - Improve the precision of our 32-bit millisecond difference

      algorithm for 32-bit Apple platforms. Fixes part of bug 27139;

      bugfix on 0.3.4.1-alpha.

    - Relax the tolerance on the mainloop/update_time_jumps test

      when running on 32-bit Apple platforms. Fixes part of bug 27139;

      bugfix on 0.3.4.1-alpha.