QVTKOpenGLWidget can not be built on platforms with GLES Qt builds
On GLES 2.0 platforms (more specifically, for Qt5 build with the "--opengl es2" option), QOpenGLFunctions_3_2_Core does not exist (i.e. it is guarded with !defined(QT_OPENGL_ES_2)).
As a result, the compilation of GUISupport/Qt/QVTKOpenGLWidget.cxx fails in QVTKOpenGLWidget::paintGL().
There are two possible alternatives to the Desktop OpenGL specific QOpenGLFunctions_3_2_Core:
Qt 5.6 adds QOpenGLExtraFunctions, which provides the glBlitFramebuffer(...) method. Qt 5.7 adds QOpenGLFramebufferObject::blitFramebuffer(...) which wraps glBlitFramebuffer.
For more information on portabel OpenGL, see: http://blog.qt.io/blog/2015/09/09/cross-platform-opengl-es-3-apps-with-qt-5-6/
glBlitFramebuffer is often provided also for GLES 2.0 platform via GL_EXT_framebuffer_blit, e.g. the RPi VC4 driver has support for it.