vrend,blitter: Unbind texture targets after use
There are more instances where the sampler view and the texture are not in the same context, and when a sampler view is still bound while in one context and the the original texture is already destroyed, then unbinding the sampler view (e.g. by binding another texture) will result in this assertion failure. So unbind textures some more.
Related: #112 (closed)
Edited by Gert Wollny