tosunits: add a missing copyright header

packages/tosunits/src/nf_ops.pas

@@ -1,3 +1,18 @@
+{
+    This file is part of the Free Pascal run time library.
+    Copyright (c) 2022 Thorsten Otto
+
+    NatFeats interface unit for Atari TOS
+
+    See the file COPYING.FPC, included in this distribution,
+    for details about the copyright.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+
 {$X+}
 {$I-}
 {$Q-}