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/gc.c b/src/gc.c
index 987ca27..54c7444 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -183,6 +183,9 @@
     // 'imactivatefunc' and 'imstatusfunc' callbacks
     abort = abort || set_ref_in_im_funcs(copyID);
 
+    // 'findfunc' callback
+    abort = abort || set_ref_in_findfunc(copyID);
+
 #ifdef FEAT_LUA
     abort = abort || set_ref_in_lua(copyID);
 #endif