patch 9.1.0831: 'findexpr' can't be used as lambad or Funcref

Problem:  'findexpr' can't be used for lambads
          (Justin Keyes)
Solution: Replace the findexpr option with the findfunc option
          (Yegappan Lakshmanan)

related: #15905
closes: #15976

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/ex_docmd.pro b/src/proto/ex_docmd.pro
index d3f1a4e..7b837c9 100644
--- a/src/proto/ex_docmd.pro
+++ b/src/proto/ex_docmd.pro
@@ -46,7 +46,10 @@
 void ex_stop(exarg_T *eap);
 void handle_drop(int filec, char_u **filev, int split, void (*callback)(void *), void *cookie);
 void handle_any_postponed_drop(void);
-int expand_findexpr(char_u *pat, char_u ***files, int *numMatches);
+int expand_findfunc(char_u *pat, char_u ***files, int *numMatches);
+char *did_set_findfunc(optset_T *args);
+void free_findfunc_option(void);
+int set_ref_in_findfunc(int copyID);
 void ex_splitview(exarg_T *eap);
 void tabpage_new(void);
 void do_exedit(exarg_T *eap, win_T *old_curwin);