patch 9.0.0618: calling function for reduce() has too much overhead

Problem:    Calling function for reduce() has too much overhead.
Solution:   Do not create a funccall_T every time.
diff --git a/src/filepath.c b/src/filepath.c
index 373a784..673cdb5 100644
--- a/src/filepath.c
+++ b/src/filepath.c
@@ -1609,7 +1609,7 @@
 	argv[0].vval.v_dict = dict;
     }
 
-    if (eval_expr_typval(expr, argv, 1, &rettv) == FAIL)
+    if (eval_expr_typval(expr, argv, 1, NULL, &rettv) == FAIL)
 	goto theend;
 
     // We want to use -1, but also true/false should be allowed.