patch 8.1.1485: double free when garbage_collect() is used in autocommand

Problem:    Double free when garbage_collect() is used in autocommand.
Solution:   Have garbage collection also set the copyID in funccal_stack.
diff --git a/src/eval.c b/src/eval.c
index 5452f45..abb3b40 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -430,12 +430,11 @@
 	vim_free(SCRIPT_SV(i));
     ga_clear(&ga_scripts);
 
-    // functions need to be freed before gargabe collecting, otherwise local
-    // variables might be freed twice.
-    free_all_functions();
-
     // unreferenced lists and dicts
     (void)garbage_collect(FALSE);
+
+    // functions not garbage collected
+    free_all_functions();
 }
 #endif