vim-patch:9.0.0634: evaluating "expr" options has more overhead than needed

Problem:    Evaluating "expr" options has more overhead than needed.
Solution:   Use call_simple_func() for 'foldtext', 'includeexpr', 'printexpr',
            "expr" of 'spellsuggest', 'diffexpr', 'patchexpr', 'balloonexpr',
            'formatexpr', 'indentexpr' and 'charconvert'.

a4e0b9785e

vim-patch:9.0.0635: build error and compiler warnings

Problem:    Build error and compiler warnings.
Solution:   Add missing change.  Add type casts.

3292a22940

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/regexp.c

@@ -2194,7 +2194,7 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
         }
         tv_clear(&rettv);
       } else {
-        eval_result[nested] = eval_to_string(source + 2, true);
+        eval_result[nested] = eval_to_string(source + 2, true, false);
       }
       nesting--;