ProjectExplorer: Give build systems a name

... and make it accessible through a variable.

Fixes: QTCREATORBUG-26147
Change-Id: I0601c09a74360b91fe8421876207a8f4ae9d75b6
Reviewed-by: hjk <hjk@qt.io>

src/plugins/qmlprojectmanager/qmlproject.h

@@ -59,6 +59,7 @@ public:
                      const Utils::FilePaths &filePaths) override;
     bool renameFile(ProjectExplorer::Node *context,
                     const Utils::FilePath &oldFilePath, const Utils::FilePath &newFilePath) override;
+    QString name() const override { return QLatin1String("qml"); }
 
     QmlProject *qmlProject() const;