patch 8.1.2107: various memory leaks reported by asan

Problem:    Various memory leaks reported by asan.
Solution:   Free the memory. (Ozaki Kiichi, closes #5003)
diff --git a/src/scriptfile.c b/src/scriptfile.c
index 92db59c..611be04 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -1358,7 +1358,10 @@
     int			i;
 
     for (i = script_items.ga_len; i > 0; --i)
+    {
 	vim_free(SCRIPT_ITEM(i).sn_name);
+	ga_clear(&SCRIPT_ITEM(i).sn_prl_ga);
+    }
     ga_clear(&script_items);
 }