CMake: Fix warning about empty filename after persisting cmake config

Change-Id: I2639059055cc42cf6ab9431f4885a01970980fca
Reviewed-by: Tim Jenssen <tim.jenssen@theqtcompany.com>

src/plugins/cmakeprojectmanager/builddirmanager.cpp

@@ -212,10 +212,8 @@ void BuildDirManager::parse()
     QTC_ASSERT(tool, return);
     QTC_ASSERT(!generator.isEmpty(), return);
 
-    // Pop up a dialog asking the user to rerun cmake
-    QString cbpFile = CMakeManager::findCbpFile(QDir(workDirectory().toString()));
-    QFileInfo cbpFileFi(cbpFile);
-
+    const QString cbpFile = CMakeManager::findCbpFile(QDir(workDirectory().toString()));
+    const QFileInfo cbpFileFi = cbpFile.isEmpty() ? QFileInfo() : QFileInfo(cbpFile);
     if (!cbpFileFi.exists()) {
         // Initial create:
         startCMake(tool, generator, intendedConfiguration());