QNX: Remove most of the CPU overhead for video rendering

This patch uses the GL_OES_EGL_image extension to create a OpenGL Texture handle
for a libscreen pixmap. If the extension is not available it uses the "old"
technique as fallback where the image data is copied into a QImage.

This reduces the CPU load by more than 70% and allows HD videos to be played jitter-free.

Task-number: QTBUG-37752

Change-Id: I4cad22c39390e4cf9eb5be5f0bfe446544a11b9e
Reviewed-by: Bernd Weimer <bweimer@blackberry.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>