patch 8.2.4173: cannot use an import in 'foldexpr'

Problem:    Cannot use an import in 'foldexpr'.
Solution:   Set the script context to where 'foldexpr' was set. (closes #9584)
            Fix that the script context was not set for all buffers.
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index ac4a51c..b0e94a0 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -18,11 +18,9 @@
 varnumber_T eval_to_number(char_u *expr);
 typval_T *eval_expr(char_u *arg, exarg_T *eap);
 int call_vim_function(char_u *func, int argc, typval_T *argv, typval_T *rettv);
-varnumber_T call_func_retnr(char_u *func, int argc, typval_T *argv);
-int call_func_noret(char_u *func, int argc, typval_T *argv);
 void *call_func_retstr(char_u *func, int argc, typval_T *argv);
 void *call_func_retlist(char_u *func, int argc, typval_T *argv);
-int eval_foldexpr(char_u *arg, int *cp);
+int eval_foldexpr(win_T *wp, int *cp);
 char_u *get_lval(char_u *name, typval_T *rettv, lval_T *lp, int unlet, int skip, int flags, int fne_flags);
 void clear_lval(lval_T *lp);
 void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv, int copy, int flags, char_u *op, int var_idx);