patch 8.2.0399: various memory leaks

Problem:    Various memory leaks.
Solution:   Avoid the leaks. (Ozaki Kiichi, closes #5803)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 58ea7c8..fb084d3 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -1346,6 +1346,18 @@
 	restore_dbg_stuff(&debug_saved);
 
     msg_list = saved_msg_list;
+
+    // Cleanup if "cs_emsg_silent_list" remains.
+    if (cstack.cs_emsg_silent_list != NULL)
+    {
+	eslist_T *elem, *temp;
+
+	for (elem = cstack.cs_emsg_silent_list; elem != NULL; elem = temp)
+	{
+	    temp = elem->next;
+	    vim_free(elem);
+	}
+    }
 #endif // FEAT_EVAL
 
     /*