fdo#66246 fdo#66395 BOM for MSVC with UTF-8 unfriendly codepage

MSVC misinterprets UTF-8 source code without BOM as ANSI/OEM codepage.
For that reason if local codepage is unfriendly to UTF-8, it sometimes
causes compilation error.

Change-Id: I8acd5500e581e020fd60b5a2ec20629f92fdf87c

sw/qa/extras/ooxmlexport/ooxmlexport.cxx

-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /*
  * This file is part of the LibreOffice project.
  *

sw/qa/extras/ooxmlimport/ooxmlimport.cxx

-/*
+/*
  * This file is part of the LibreOffice project.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public

sw/qa/extras/rtfexport/rtfexport.cxx

-/*
+/*
  * This file is part of the LibreOffice project.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public

sw/qa/extras/rtfimport/rtfimport.cxx

-/*
+/*
  * This file is part of the LibreOffice project.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public

vcl/win/source/window/keynames.cxx

-/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /*
  * This file is part of the LibreOffice project.
  *