patch 8.2.3868: Vim9: function test fails

Problem:    Vim9: function test fails.
Solution:   Add missing changes.  Add test for earlier patch.

patch 8.2.3867: implementation of some list functions too complicated

Problem:    Implementation of some list functions too complicated.
Solution:   Refactor do_sort_uniq(), f_count() and extend() (Yegappan
            Lakshmanan, closes vim#9378)

patch 8.2.3866: Vim9: type checking global variables is inconsistent

Problem:    Vim9: type checking global variables is inconsistent.
Solution:   Use the "unknown" type in more places.

patch 8.2.3865: Vim9: compiler complains about using "try" as a struc…

…t member

Problem:    Vim9: compiler complains about using "try" as a struct member.
Solution:   Rename "try" to "tryref".

patch 8.2.3864: cannot disable requesting key codes from xterm

Problem:    Cannot disable requesting key codes from xterm.
Solution:   Add the 'xtermcodes' option, default on.

patch 8.2.3863: various build flags accidentally enabled

Problem:    Various build flags accidentally enabled.
Solution:   Revert several lines in Makefile.

patch 8.2.3862: crash on exit with EXITFREE and using win_execute()

Problem:    Crash on exit with EXITFREE and using win_execute().
Solution:   Also save and restore tp_topframe. (issue vim#9374)

patch 8.2.3861: list of distributed files is outdated

Problem:    List of distributed files is outdated.
Solution:   Add new files.

patch 8.2.3860: Vim9: codecov struggles with the file size

Problem:    Vim9: codecov struggles with the file size.
Solution:   Split vim9compile.c into four files.

patch 8.2.3859: Vim9: some code lines not tested

Problem:    Vim9: some code lines not tested.
Solution:   Add a few specific tests.