Update dx9sdk (got rid of redundant headers)
Try to simplify alpha replace for poor compilers.
Clear stencil on switch from 565 buffer.

Fixes #2094, shadows in Kingdom Hearts in some scenes.

Not a complete solution, but should be a relatively safe one.
Merge pull request #6852 from unknownbrackets/gpu-minor

Clear stencil/alpha when switching from 565, minor frag shader simplication