Fixes for Silent Hill: Origins (depth buffer reassignment, eliminate readback)

[hrydgard]

If a framebuffer starts using a different depth buffer address than before, re-point. This fixes an issue where the wrong depth buffer was being copied from in Silent Hill Origins, causing weird artifacts like this:

Ideally we should copy off the depth buffer to another framebuffer that's still pointed at that depth buffer, but in practice this is not very likely to be needed. We'll implement it if we find it is.

Plus, use a compat setting to eliminate readbacks (to improve performance), and reduce some logging.

(This does not fix shadows, that's a separate problem)

See issue #16126