Qt: Pick tool chain that works with the default mkspec

Pick a tool chain that suggests the same mkspec as the Qt version
was build with if possible.

This should help with the case of us choosing the wrong tool chain
on mac.

Change-Id: I206658fd36f2f3c2223392a2c69cf264b5b6a54e
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/qt4projectmanager/qt4target.cpp

@@ -292,6 +292,20 @@ QList<ProjectExplorer::ToolChain *> Qt4BaseTarget::possibleToolChains(ProjectExp
     return result;
 }
 
+ProjectExplorer::ToolChain *Qt4BaseTarget::preferredToolChain(ProjectExplorer::BuildConfiguration *bc) const
+{
+    Qt4BuildConfiguration *qtBc = qobject_cast<Qt4BuildConfiguration *>(bc);
+    if (!qtBc || !qtBc->qtVersion())
+        return Target::preferredToolChain(bc);
+
+    QList<ProjectExplorer::ToolChain *> tcs = possibleToolChains(bc);
+    const QString mkspec = qtBc->qtVersion()->mkspec();
+    foreach (ProjectExplorer::ToolChain *tc, tcs)
+        if (tc->mkspec() == mkspec)
+            return tc;
+    return tcs.isEmpty() ? 0 : tcs.at(0);
+}
+
 void Qt4BaseTarget::removeUnconfiguredCustomExectutableRunConfigurations()
 {
     if (runConfigurations().count()) {

src/plugins/qt4projectmanager/qt4target.h

@@ -90,6 +90,7 @@ public:
     virtual QList<ProjectExplorer::RunConfiguration *> runConfigurationsForNode(ProjectExplorer::Node *n) = 0;
 
     QList<ProjectExplorer::ToolChain *> possibleToolChains(ProjectExplorer::BuildConfiguration *bc) const;
+    ProjectExplorer::ToolChain *preferredToolChain(ProjectExplorer::BuildConfiguration *) const;
 
 signals:
     void buildDirectoryInitialized();