CppTools: Call ProjectInfo::finish when we get it

No need to require the project managers to do this. Also, it is easy to
forget.

Change-Id: I96f7a5e5547418678af9653e5753c372f0880e5a
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -473,8 +473,6 @@ void QmakeProject::updateCppCodeModel()
         }
     }
 
-    projectInfo.finish();
-
     CppTools::GeneratedCodeModelSupport::update(generators);
     m_codeModelFuture = CppTools::CppModelManager::instance()->updateProjectInfo(projectInfo);
 }