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/evalvars.c b/src/evalvars.c
index fa52e96..187670a 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2628,7 +2628,7 @@
     if (*name == 'v')				// v: variable
 	return &vimvarht;
     if (get_current_funccal() != NULL
-	       && get_current_funccal()->func->uf_dfunc_idx == UF_NOT_COMPILED)
+	       && get_current_funccal()->func->uf_def_status == UF_NOT_COMPILED)
     {
 	// a: and l: are only used in functions defined with ":function"
 	if (*name == 'a')			// a: function argument