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/option.h b/src/option.h
index 641514d..d5f72a1 100644
--- a/src/option.h
+++ b/src/option.h
@@ -597,7 +597,7 @@
 EXTERN char_u	*p_ft;		// 'filetype'
 EXTERN char_u	*p_fcs;		// 'fillchar'
 #ifdef FEAT_EVAL
-EXTERN char_u	*p_fexpr;	// 'findexpr'
+EXTERN char_u	*p_ffu;		// 'findfunc'
 #endif
 EXTERN int	p_fixeol;	// 'fixendofline'
 #ifdef FEAT_FOLDING
@@ -1171,11 +1171,11 @@
     , BV_EP
     , BV_ET
     , BV_FENC
-    , BV_FEXPR
     , BV_FP
 #ifdef FEAT_EVAL
     , BV_BEXPR
     , BV_FEX
+    , BV_FFU
 #endif
     , BV_FF
     , BV_FLP