This avoids including ex_eval.h in any other header, thus preventing
future circular includes.

Work on https://github.com/neovim/neovim/issues/459

Add space around arithmetic operators '+' and '-'.
Remove space between back-to-back parentheses, i.e. ')(' vs. ') ('.
Remove space between '((' or '))' of control statements.
Add space between ')' and '{' of control statements.
Remove space between function name and '(' on function declaration.
Collapse empty blocks between '{' and '}'.
Remove newline at the end of the file.
Remove newline between 'enum' and '{'.
Remove newline between '}' and ')' in a function invocation.
Remove newline between '}' and 'while' of 'do' statement.

Problem:    Still crash with error in :catch and also in :finally.
Solution:   Only call finish_exception() once. (closes vim/vim#8954)
https://github.com/vim/vim/commit/f67d3fb7363ebc9454f9bb582de3978609a4fd6b

Exclude CSF_FUNC_DEF change (Vim9script).

https://github.com/vim/vim/commit/4197828dc666f2d258594f7f9461534d23cc50e4

Cherry-pick the changes to existing flags values.
Required for v8.2.3478.

That patch mostly relates to Vim9script, but I'm careful not to mark it N/A in
case the flags have some use outside of Vim9 in the future.

Excludes CSF_FUNC_DEF (flag introduced in v8.2.1870 for Vim9's block scopes).

Problem:    Giving error messages is not flexible.
Solution:   Add semsg().  Change argument from "char_u *" to "char *", also
            for msg() and get rid of most MSG macros. (Ozaki Kiichi, closes
            vim/vim#3302)  Also make emsg() accept a "char *" argument.  Get rid of
            an enormous number of type casts.
https://github.com/vim/vim/commit/f9e3e09fdc93be9f0d47afbc6c7df1188c2a5a0d

* refactor: format all C files under nvim
* refactor: disable formatting for Vim-owned files:
    * src/nvim/indent_c.c
    * src/nvim/regexp.c
    * src/nvim/regexp_nfa.c
    * src/nvim/testdir/samples/memfile_test.c

Problem:    Not using a typedef for condstack.
Solution:   Add a typedef.
https://github.com/vim/vim/commit/ddef129160ff0676e5da482071fb2fdc2988ac34

Problem:    No comma after last enum item.
Solution:   Add a few commas to check if this works for all compilers.  Also
            add a few // comments.
https://github.com/vim/vim/commit/ea3ece405ab55f44018257bd2f5021231af8e87f