Debugger: Add toolchain combos to start dialogs, refactor detection.

Add combo box listing toolchains with debuggers to start external,
attach and core.
Another attempt at streamlining engine detection:
Split in detection functions that first collect a list of
available engines by preference, then remove disabled and
wrongly configured engines and use the remaining best.
matching. checkconfiguration is now the central place where
engine detection and config check takes place.

Rubber-stamped-by: hjk

src/plugins/debugger/debuggertoolchaincombobox.cpp

@@ -0,0 +1,90 @@
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2011 Nokia Corporation and/or its subsidiary(-ies).
+**
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** No Commercial Usage
+**
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+**
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**************************************************************************/
+
+#include "debuggertoolchaincombobox.h"
+
+#include <projectexplorer/toolchainmanager.h>
+#include <utils/qtcassert.h>
+
+#include <QtCore/QFileInfo>
+
+Q_DECLARE_METATYPE(ProjectExplorer::Abi)
+
+namespace Debugger {
+namespace Internal {
+
+DebuggerToolChainComboBox::DebuggerToolChainComboBox(QWidget *parent) :
+    QComboBox(parent)
+{
+}
+
+void DebuggerToolChainComboBox::init(bool hostAbiOnly)
+{
+    const ProjectExplorer::Abi hostAbi = ProjectExplorer::Abi::hostAbi();
+    foreach (const ProjectExplorer::ToolChain *tc, ProjectExplorer::ToolChainManager::instance()->toolChains()) {
+        if (!hostAbiOnly || hostAbi.isCompatibleWith(tc->targetAbi())) {
+            const QString debuggerCommand = tc->debuggerCommand();
+            if (!debuggerCommand.isEmpty()) {
+                const QString name = tr("%1 (%2)").arg(tc->displayName(), QFileInfo(debuggerCommand).baseName());
+                addItem(name, qVariantFromValue(tc->targetAbi()));
+            }
+        }
+    }
+    setEnabled(count() > 1);
+}
+
+void DebuggerToolChainComboBox::setAbi(const ProjectExplorer::Abi &abi)
+{
+    QTC_ASSERT(abi.isValid(), return; )
+    const int c = count();
+    for (int i = 0; i < c; i++) {
+        if (abiAt(i) == abi) {
+            setCurrentIndex(i);
+            break;
+        }
+    }
+}
+
+ProjectExplorer::Abi DebuggerToolChainComboBox::abi() const
+{
+    return abiAt(currentIndex());
+}
+
+ProjectExplorer::Abi DebuggerToolChainComboBox::abiAt(int index) const
+{
+    return index >= 0 ? qvariant_cast<ProjectExplorer::Abi>(itemData(index)) :
+                        ProjectExplorer::Abi();
+}
+
+} // namespace Debugger
+} // namespace Internal