patch 8.2.1023: Vim9: redefining a function uses a new index every time

Problem:    Vim9: redefining a function uses a new index every time.
Solution:   When redefining a function clear the contents and re-use the
            index.
diff --git a/src/eval.c b/src/eval.c
index b4e2c2f..38afc24 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -253,7 +253,7 @@
 	    return FAIL;
 
 	if (partial->pt_func != NULL
-			  && partial->pt_func->uf_dfunc_idx != UF_NOT_COMPILED)
+			  && partial->pt_func->uf_def_status != UF_NOT_COMPILED)
 	{
 	    if (call_def_function(partial->pt_func, argc, argv,
 						       partial, rettv) == FAIL)