Fixes: pluginmanager: fork QPluginLoader and QLibraryPrivate

Details:  saves 20% startup time. patch for Qt 4.6 at
http://codepaster-nokia.troll.no/?id=11918.

src/libs/extensionsystem/pluginmanager.cpp

@@ -39,7 +39,6 @@
 #include "iplugin.h"
 
 #include <QtCore/QMetaProperty>
-#include <QtCore/QPluginLoader>
 #include <QtCore/QDir>
 #include <QtCore/QTextStream>
 #include <QtCore/QWriteLocker>

src/libs/extensionsystem/pluginspec.cpp

@@ -42,10 +42,23 @@
 #include <QtCore/QFileInfo>
 #include <QtCore/QXmlStreamReader>
 #include <QtCore/QRegExp>
-#include <QtCore/QPluginLoader>
 #include <QtCore/QCoreApplication>
 #include <QtDebug>
 
+#define USE_UNPATCHED_QPLUGINLOADER 1
+
+#if USE_UNPATCHED_QPLUGINLOADER
+
+#include <QtCore/QPluginLoader>
+typedef QT_PREPEND_NAMESPACE(QPluginLoader) PluginLoader;
+
+#else
+
+#include "patchedpluginloader.cpp"
+typedef PatchedPluginLoader PluginLoader;
+
+#endif
+
 /*!
     \class ExtensionSystem::PluginDependency
     \brief Struct that contains the name and required compatible version number of a plugin's dependency.
@@ -770,7 +783,7 @@ bool PluginSpecPrivate::loadLibrary()
 
 #endif
 
-    QPluginLoader loader(libName);
+    PluginLoader loader(libName);
     if (!loader.load()) {
         hasError = true;
         errorString = loader.errorString();