ClangSupport: Remove not used interface

Change-Id: I0e7ea2ba6dfdf651bbb509a07e866be614e01554
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/libs/clangsupport/clangsupport.pro

@@ -1,5 +1,4 @@
 include(../../qtcreatorlibrary.pri)
 include(clangsupport-lib.pri)
 
-HEADERS += \
-    commandlinebuilderinterface.h
+HEADERS +=

src/libs/clangsupport/commandlinebuilderinterface.h

@@ -1,41 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of Qt Creator.
-**
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3 as published by the Free Software
-** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-3.0.html.
-**
-****************************************************************************/
-
-#pragma once
-
-#include <utils/smallstringvector.h>
-
-namespace ClangBackEnd {
-
-class CommandLineBuilderInterface
-{
-public:
-    virtual Utils::PathStringVector create() = 0;
-
-protected:
-    ~CommandLineBuilderInterface() = default;
-};
-
-} // namespace ClangBackEnd