Build fails if Qt configured with -no-stl

Qt 4.7.4 configured with -no-stl.

Following build instructions for qt-quick3d (master) results in:

qailoader.cpp: In member function 'void QAiLoader::loadMesh(aiMesh*)':
qailoader.cpp:132: error: 'class QString' has no member named 'toStdString'
qailoader.cpp:150: error: 'class QString' has no member named 'toStdString'
qailoader.cpp:160: error: 'class QString' has no member named 'toStdString'
qailoader.cpp:167: error: 'class QString' has no member named 'toStdString'
qailoader.cpp: In member function 'QGLSceneNode* QAiLoader::loadMeshes()':
qailoader.cpp:283: error: 'class QString' has no member named 'toStdString'
qailoader.cpp: In member function 'void QAiLoader::loadTextures(aiMaterial*, QGLMaterial*)':
qailoader.cpp:426: error: 'class QString' has no member named 'toStdString'
qailoader.cpp:439: error: 'class QString' has no member named 'toStdString'
qailoader.cpp:453: error: 'class QString' has no member named 'toStdString'

Suggested solution: remove dependence on QString::toStdString()