Port Qt Creator to the new plugin system of Qt 5.

- Add Q_PLUGIN_METADATA for Qt 5, use Q_EXPORT_PLUGIN
  for Qt 4.
- Generate the Json files for Qt 5 from the pluginspec
  files by using a XSLT sheet.

Change-Id: I8653f182ae7d61615971c093df10b84fb06c2172
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/libs/extensionsystem/iplugin.h

@@ -36,6 +36,9 @@
 #include "extensionsystem_global.h"
 
 #include <QObject>
+#if QT_VERSION >= 0x050000
+#    include <QtPlugin>
+#endif
 
 namespace ExtensionSystem {
 
@@ -83,4 +86,16 @@ private:
 
 } // namespace ExtensionSystem
 
+// The macros Q_EXPORT_PLUGIN, Q_EXPORT_PLUGIN2 become obsolete in Qt 5.
+#if QT_VERSION >= 0x050000
+#    if defined(Q_EXPORT_PLUGIN)
+#        undef Q_EXPORT_PLUGIN
+#        undef Q_EXPORT_PLUGIN2
+#    endif
+#    define Q_EXPORT_PLUGIN(plugin)
+#    define Q_EXPORT_PLUGIN2(function, plugin)
+#else
+#    define Q_PLUGIN_METADATA(x)
+#endif
+
 #endif // IPLUGIN_H