Fix VSFilter compilation after fd11028d826de05d59f7cfbe2e616a620524d5f1.
Fix: Post-resize shaders weren't working with VMR-9 (renderless).

The required interface wasn't put in the interfaces list and was still available by chance for the EVR renderers. As a consequence, the m_pMFVDC interface wasn't available for some EVR renderers while to should have been. To keep the behavior consistent with older builds, the order of some checks for m_pMFVDC has been changed.

Also remove the hack that was used for MadVR since it's now correctly fixed.

This commit fixes ticket #2839.
VSFilter: Removed remaining BYTE* casts.
Fix VSFilter compilation after 6c7c8e59e0e8da635cd2abf30f34549fbf88b1de.
Fix "Unitialized variable".