Cocoa: Make the hellowindow opengl example work.

Cocoa: Make the hellowindow opengl example work.

You're not supposed to use NSOpenGLView and
NSOpenGLContext at the same time - it's one or
the other. Qmlscene worked because it was hitting
the raster path that doesn't have a NSOpenGLView.

Remove the NSOpenGLView path and m_windowSurfaceView.

Change-Id: I10358851a94cd1780a312af09bbb7cf5db8f984f
Reviewed-on: http://codereview.qt.nokia.com/3862
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>