Sorts out references that cause some modules to be kept around after
backend shutdown.

Should also solve the issue with errors being thrown due to the config
being loaded after device creation, leading to the incorrect device being
used in a multi-adapter system.

Moves render target restoring to RestoreAPIState, this also means no need
to manually restore after allocating in a buffer that caused execution,
because the manager restores it for us.

Remove a method that wasn't used from D3DUtil.cpp, and fixes a few errors
in EFB poke drawing.

The D3D backend was always forcing Anisotropic filtering when that is enabled regardless of how the game chose to configure the texture filtering registers; this causes the same issues as "Force Filtering" without Anisotropy, such as causing game UI elements to no longer line up adjacent correctly. Historically, OpenGL's Anisotropy support has always worked "better" than D3D's due to seeming to not have this problem; unfortunately, OpenGL's Anisotropy specification only gives GL_LINEAR based filtering modes defined behavior, with only the mipmap setting being required to be considered. Some OpenGL implementations were implicitly disabling Anisotropy when the min/mag filters were set to GL_NEAREST, but this behavior is not required by the spec so cannot be relied on.

Remove uninitialized non-static variable. Replace test to avoid unnecessary state changes with a simpler one.