[d3d9] SIMPLIFIED: Only dirty frame buffer on render state changes if render area is impacted

[K0bin]

Simplified version of #4349 that removes some tracking.
It removes some more tracking that has kind of bothered me.

[doitsujin]

I like this approach more, however I think we need to do two passes over the render target array:

• one to determine the actual render area from only actively written RTV/DSV
• one to filter out non-written RTV/DSV that are actually smaller than the render area

Otherwise we'll filter out false positives, especially if an active DSV is what actually limits the render area.