Add <platform> element to pluginspec-files.

The <platform> element may contain a regular expression
matching the names of the platforms on which the plugin works.

Task-number: QTCREATORBUG-9002
Change-Id: Ic816cfed69a5dd2c4112c976843b9106ba2cbd22
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>

src/libs/extensionsystem/pluginspec_p.h

@@ -36,6 +36,7 @@
 #include <QObject>
 #include <QStringList>
 #include <QXmlStreamReader>
+#include <QRegExp>
 
 namespace ExtensionSystem {
 
@@ -72,6 +73,7 @@ public:
     QString description;
     QString url;
     QString category;
+    QRegExp platformSpecification;
     QList<PluginDependency> dependencies;
     bool enabledInSettings;
     bool disabledIndirectly;