Enable macro editing for the Clang indexer

Refactor much of the code from Environment* classes to NameValue* classes
to share it with the preprocessor macro settings.

Change-Id: Ica4ee817aa338230c422b30d91240d266248d226
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/clangpchmanager/clangindexingsettingsmanager.cpp

@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 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.
+**
+****************************************************************************/
+
+#include "clangindexingsettingsmanager.h"
+
+#include "clangindexingprojectsettings.h"
+
+namespace ClangPchManager {
+
+ClangIndexingSettingsManager::ClangIndexingSettingsManager() = default;
+
+ClangIndexingSettingsManager::~ClangIndexingSettingsManager() = default;
+
+ClangIndexingProjectSettings *ClangIndexingSettingsManager::settings(ProjectExplorer::Project *project)
+{
+    auto &setting = m_settings[project];
+
+    if (!setting)
+        setting = std::make_unique<ClangIndexingProjectSettings>(project);
+
+    return setting.get();
+}
+
+void ClangIndexingSettingsManager::remove(ProjectExplorer::Project *project)
+{
+    m_settings.erase(project);
+}
+
+bool ClangIndexingSettingsManager::hasSettings(ProjectExplorer::Project *project) const
+{
+    return m_settings.find(project) != m_settings.end();
+}
+} // namespace ClangPchManager