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/optionstr.c b/src/optionstr.c
index d82b8e1..0554c0e 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -313,6 +313,7 @@
     check_string_option(&buf->b_p_tsrfu);
 #endif
 #ifdef FEAT_EVAL
+    check_string_option(&buf->b_p_ffu);
     check_string_option(&buf->b_p_tfu);
 #endif
 #ifdef FEAT_KEYMAP
@@ -324,9 +325,6 @@
     check_string_option(&buf->b_p_efm);
 #endif
     check_string_option(&buf->b_p_ep);
-#ifdef FEAT_EVAL
-    check_string_option(&buf->b_p_fexpr);
-#endif
     check_string_option(&buf->b_p_path);
     check_string_option(&buf->b_p_tags);
     check_string_option(&buf->b_p_tc);
@@ -3135,9 +3133,8 @@
 #if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * One of the '*expr' options is changed: 'balloonexpr', 'diffexpr',
- * 'findexpr', 'foldexpr', 'foldtext', 'formatexpr', 'includeexpr',
- * 'indentexpr', 'patchexpr', 'printexpr' and 'charconvert'.
- *
+ * 'foldexpr', 'foldtext', 'formatexpr', 'includeexpr', 'indentexpr',
+ * 'patchexpr', 'printexpr' and 'charconvert'.
  */
     char *
 did_set_optexpr(optset_T *args)