In blender 2.79 you could use a render result as a camera background image. This is useful during layout/compositing. During Blender 2.80 development there were 2 issues introduced that removed this feature. * to receive a render result the image required a lock. This lock wasn't passed and therefore no image was read from the result. Generating an GPUTexture from an Blender image also didn't do the locking. * the iuser->scene field wasn't set what is required for render results. This change adds an optional `ibuf` parameter to `GPU_texture_from_blender` that can be passed when available. Reviewed By: fclem, brecht Differential Revision: https://developer.blender.org/D6684